Have you taken any antibiotics in the past few months? I went through something similar about 10 years ago and turned out it was drug-induced lupus. It went away, but took awhile. The scary part is that the problems didn't show up until well after I had finished the round - months later. And, it was all due to taking the antibiotic Levaquin. I actually got to the point where I could not stand up I was so weak.