Summer (not heat) Intolerance

All winter I thought about summer as an amazing time of year when I would feel better. April came along and sure enough I started being able to do WAY more than during the winter. May was a busy month and while I didn't always feel great I was able to keep going. June however, has been less than wonderful. I've had to quit and cancel most everything, but I still feel well enough to be very annoyed with being stuck on the couch! There doesn't seem to be a direct correlation with the heat. For instance I tend to feel especially yucky right after it rains even though it is cooler then. Here in Terre Haute summers are normal around 85-90F with 70-100% humidity (at least recently). My current thoughts are- 1. Too much humidity. I am normally able to keep myself cool, but maybe the humidity is pushing me over the edge. 2. Can't handle the difference between hot outside and cold inside (my parents home is kept at 70F). 3. This may sound silly, but do you think I could still be dealing with cold intolerance? After all, 70 degrees is not very warm and I sleep about 12 hours a night, which means I'm inside at least half of every day. Other suggestions would be welcome!