lyme disease, erythema chronicum migrans
"For Lyme symptoms (which vary over months) I've taken different antibiotics for more than a year. Most of that time I took a different medicine (Ceftin), then IV, then Doxycycline which was not quite strong enough to stop the last of my symptoms (spine pain and arthritis in my hands) so for 30 days I took BOTH the Doxy   azithromycin. There was almost immediate improvement (100% in spine!) but not completely resolved in hands. Currently doing another 30 days of both antibiotics. Side effects: there are hot flashes, like night sweats, for about 5 minutes every hour, but that may be caused by Lyme. The only gut problems may be my fault for taking it on an empty stomach then starting the day with black coffee. (Yeah -- don't do that.)"