Suddenly Heart Problems While Smoking. Never Had These Before...

I have been smoking for a few years now and have always enjoyed it and never had any problems. I smoke about every other day. 90% of the time with friends. Recently though i have been having these issues with my heart and these sort of panic attacks that i can't explain when i get high. 
 
Now whenever i smoke i have always had side effects that i have grown used to...
 
My legs FEEL like they are shaking when visibly they usually aren't. This leads me to me tapping my foot or sitting on my legs since i feel like i have to mask my legs shaking from people that might notice. They sometimes do actually shake but most of the time they just feel like they are. It almost sometimes feels like tiny muscles relaxing and contracting over and over all through my legs . It feels strongest like this around my groin area. 
 
I also always get really COLD feeling. I don't think i am actually physically cold but i always want to bundle up while high. It also reduces that leg shaking feeling when i'm all bundled up (usually stops it all together). Like the other day it was like 80 degrees outside and my room was pretty damn hot. Before i starting smoking i had a fan on me and i was kinda sweaty. After smoking i found myself in sweatpants, a hoody, AND a freakin robe. Even though i was practically sweating not even 15 minutes earlier, i then didn't even notice the heat and was no longer sweating, just really comfy. After the high mostly wore off i started to get really hot again and had to shed my layers to stay cool. 
 
Those two side effects i have lived with and never really paid much attention too. I figured its just because i'm really skinny (a tad underweight) or something and already have a super fast metabolism as it is. Maybe its just my body going into overdrive or something when i smoke. 
 
 
This new side effect though had been very unpleasant and i may quit smoking all together because of it. At some point whatever i am doing (playing a game or watching something usually) everything suddenly becomes too intense (like i suddenly get super overwhelmed by the simplest tasks) and i cant handle it and need to stop. Last time it happened i was doing something VERY easy. I was just trying to make a new Mii character on my friends Wii. My heart starts beating VERY fast and i get kind of confused or dazed or something. Then it quickly turns into a panicky feeling and my chest feels kinda warmish. I can't really explain it but i find my self holding my chest or putting pressure on it with my arms or knees depending on how i'm sitting. Nothing in my chest hurts or anything but it just feels more comforting to have something pushing on it when i get this way. Sometimes i feel like i need to stand up and so i pace around a little then sit back down. I usually start thinking differently and sometimes say things that aren't normal for me (if other people are around when it happens). Just stupid shit like "maaaan you can have the rest of my stash, i think i gotta stop smoking for good" or "im kinda freaking out man i just gotta calm down we gotta stop what we are doing". Probably because it becomes hard to think clearly. Lots of irrational thoughts start flowing as well. Whatever i try though i can never get my heart rate down. Sometimes it lasts as long as 40 minutes of just fast beating. I have tried breathing techniques and doing something calm and stuff like that but it never really helps. The super fast heartbeat is always there in the background overpowering anything i try to distract myself with. The following day i usually feel way more drained than usual and occasionally a slight soreness of the chest.
 
This doesn't happen every time that i smoke but since it started last month it has happened probably 4 times or so. I think it only happens now when i smoke a lot (which isn't really a lot). It doesn't really make sense since i have been smoking for years and have downed multiple blunts on multiple occasions in the past with no problems what so ever. Now "a lot" is like 2-3 bowls (shared). It's like my tolerance has suddenly taken a massive drop out of nowhere. I don't get very high anymore since i'm limiting myself to 1-2 bowls so i dont have another episode. If i push more than 2 bowls then i usually start to feel that panicked feeling at some point. I'm not even super high when it happens (since i am limiting myself now in fear). So i can rule out that it's just a new side effect of being "too high". 
 
I have gone to my doctor and everything is normal apparently. Blood sugar is fine and i have had my heart checked with one of those graph things and they said everything checks out. I have a few times experienced a heart palpitation (feels like it skips a beat 5-6 separate times throughout a day or something) while not high but my doctor says lots of people have them and not to worry. He said its only bad if many are happening in a short period of time, which never happens to me. 
 
So i'm thinking it might be just in my head? But my question is why now? Nothing has changed over the years that i can think of that would cause this to happen. Just figured i would try my story here and see if anyone has experienced something similar and maybe had some advice to combat it. I just don't want to die because of some unchecked heart issue i suddenly have that the weed might be aggravating. 
 
 

 

Thank you for the reply. I thought about that but i dont think that's it. Each time i have had this problem it has been with a different smoking apparatus each time. Also the people i smoke with never had any problems themselves.