What is wrong with my legs!?

Sounds like a clic case of busted legs. That's why in the military we don't run 5 days a week no more during training. Too much stress on the legs will make them "bust". You get better results from exercising the legs strenuously every other day instead of every day. Now I'm not sure what "busted legs" means in medical terms but I do know your putting too much stress, too often on them.