I have been taking Doxycycline Hyclate 100mg twice a day for 6 days for a tick bite infection. I've developed a rash on the palm of my left hand. It doesn't itch, but burns a little. My doctor says it's not an allergic reaction. I need to get rid of my illness, and the rash really doesn't bother me that much. What I fear are what internal side effects I might be having from reacting to the medicine.