First - go see your doc and get a physical, if you haven't done so in a while.

I'd agree with Creatre - get some rest. Take a week off the bike and do something else - swim, walk, run, lift some weights. Let your body recover. Outside a need to train 6 days a week - consider riding just 3-4 days, and then mix in some other activities on the off days.

Sounds like maybe you're eating a bit too much on your rides, which can cause cramps especially when mixed with sports drinks. If you've been living and riding in the heat for 10 years - you're 10 years older. Your body might be telling you something.....