Can somebody please tell me whats wrong with my plant?

light
what kind of and how strong

Temps and humidity (looks like heat and no humidity to me)
give us a good look at and the description or brand of soil

watering
how often are you watering and how much
are you using chlorinated water?

air movement
how and how much and how strong

nutes
what you are using how often and how much

 

Too hot too dry. FYI if room temp reaches 80 you can bet its 90+ under your light unless you have air circulation or are taking the temp from the top of the plants.

 

Also with big lights like that make sure they are 12-18in away from the canopy.

Humidity is ideal at 40-60%

Don't know if you drilled those holes yet but you really should have drain holes don't worry about the roots if you happen to get one its not the end of the world more will grow.

 

That's a pretty hot light for a small plant. Get it far away as you can for now. Is it possible to use 4 cfl's within 8" for a few weeks. That will drive down temps if they are high. 80's is good when it gets over 87 it's starting to hurt. 90 is where ya say I got problems. Get a small fan in the floor and be sure the leaves always vibrate. Ya don't want them flapping. You need to get the humidity up during veg. Especially a Sativa strain. That looks Sativa. They like the heat, but they need humidity and lots of air flow. Mist every time you look in and if your humidity is that low they are not getting very wet I think. Get some good grow pots. If you get the Fabric NoobWannaB has a good thread on a SIP system that waters itself I use too. That also keep humidity up. Don't get caught up in myths.
Watering. Flood and dry. That's how, water through and always come later and water through again. You DO need holes if you are new to growing and don't quite read a plant from across the room. Get a nursery grow pots with plenty holes in the bottom or smart pots (fabric). You never worry about tearing or breaking roots unless she is late flower and sometimes then it's called for in a special way. Not your worry now. When you repot you should break the roots at the very bottom and sides to open them to spread out to new soil so don't worry about breaking roots. If you want to reduce the size of the plant you can just about cut them all off to fit the size pot you want and the plant will still grow.

Hope this helps but if I missed something ask, I will check back.

 

Yeah really no need to worry about stretching with a 600 mh

 

put used coffee grounds on the top of the soil. I did last night and saw one this morning. this is a place wherre you walk in and disrupt the airflow and they fly. The coffee grounds worked over night. This is not an invitation to over do or to use straight coffee. Top dress only with the used ones or the filters. Then just stir into the top a little but so it is still thick on the top where they surface.

Air needs to move all of the time. Still air is your enemy, bugs and molds and fungus friends. Vibrations are the key you plants should have good vibrations but that doesn't mean they are flapping in the wind.
You've got time, go with the flow and don't fret, there is almost always a way out or a simple fix at hand. She is a lil hot looking light burned but she will adjust but I thought a lil more shady light for a few days would help her get caught up. I think if you get the humidity up and get the right pots and mist when you open the cab maybe a lil tray of water. All your new growths should come in fine. When you think you have troubles, you just saw it cause it just showed it. It had the problem already days before. It may have adjusted. Most of the time you will find if you are doing all the things that the thing will adjust if you are patient. The results don't show right away. Damaged growth and foliage is always that but the new growth vigor show strength and happiness. I always remove damaged stuff but it is a personal choice.
Nutes,
The way I have always done is to mix half strength to a gallon of water while they are young and less than 2 ft. and not in a 10 gallon pot which it shouldn't be. Then before lights out I make certain the plant is well watered then drench the top. 3 to 5 gallon pot would be about a quart or 2 depending on how big the plant and how badly she needs it. Don't overdo and expect magic it is disaster. When you plant grows toward 3ft and hardens some then start the full strength. Now if you know different about the measures of your chosen product and you are experienced use what you know about your grow and ability and apply it to your method. I use organics but I have used other things and they all will work fine if bugs and disease don't get them first. good luck buddy

 

The coffee thing supposedly works on all bugs and good for the plant. If you have some earth worms throw them in there too.

 

yep but if you can afford to buy and keep on hand a bag of worm castings that is like medicine you shouldn't be without. I buy them to keep on hand and use my bed mostly for the garden because it isn't very old yet. If a plant is having trouble the first thing I do is top dress and water in. I keep a worm bed too and sometimes I go get some and throw a few in there.
be sure they are Earth worms like you fish with.

 

let me see them and did you feed recently? did you repot yet? what have you done in the last 3 days?

 

If you fed it 2 days ago flood it and dilute what you put on her. In other words its showing you it was too hot for the size and age or maybe too much of the diluted. Just flush it out. Pour water through and lift the pot off the floor and blow a small fan on it at the dirt and she will be fed and come right through. I really need to see it but that is my instinct. Over feeding is one of the few times I stress immediate action. You can save her I'm pretty sure but I need to see how far gone she is. My friend Skinnybigbuds went through this with 2 and got one through it.