Well I sure hope that we can help get ya past the finish line on this grow! Just need some basic info from ya first, maybe it'll entice some of our lurking vets to chime in!
What kind of soil are ya growing in? Are you/have you applied any nutrients or additives? In soil you generally don't have to fret near as much about PH as, per say, a coco or hydro grower. But if you're in a soilless mix (if I'm using that term correctly), ph may be more of a concern. I'm not seeing raised edges, and I'm not seeing the damage being concentrated to the canopy where the most direct light is being recieved, so I very seriously doubt that your issue is heat stress. Would it be possible for us to get a pic of the entire plant? Also, have you inspected for bugs? I dont know if bugs could cause this or not, but it is still worth ruling out. Outdoors is a different world than growing indoors...but I'm sure you will get it down pat!