Blacked out from smoking weed?!!

about a year ago I had a surgery for my scoliosis, when I came home from the hospital I smoked with some friend thinking it would help with the pain (this was during the summer so it was very hot also), I took a few hits off the blunt and began feeling very weird, my feet felt very light, i started to feel very hot, and i began to lose vision, i believe i blacked out for about five seconds or so, i then smoked a couple times after that and it happened again so I figured it was cuz of the surgery so i waited a while and let myself fully recover, i recently just started smoking again and it was all going good but I went to a concert last night and I smoked in the mosh pit, it then happened again. My friend helped me get out the mosh and find some water and cold air and i felt normal again, I’m really concerned about this, is it because i had the surgery? Should i not smoke when it’s hot? Or should i just stop smoking all together? Please help!!