M.L.
I am really sensitive to heat as well, I get overheated very easily and am prone to heat exhaustion. So is my son. It is a condition that runs in our family, I do not remember the proper medical term for it. This could be what is happening with you, its very easy to get cranky when you don't feel well. I'd see your doctor. Also, extreme irritability can be due to several different mental conditions. No, I am not saying you are crazy. Depression is one of those issues. I have dealt with depression for years and my main symptem was irritablibilty and flying off the handle about particular issues. With Therapy and medication I felt like a different person. I would start with my doc, if there are no physical reasons for it, they should refer you to a psychologist. Good Luck.