I was prescribed doxycycline for possible lyme disease as a precautionary measure after a tick bite followed by a rash and fever. I took only two doses, and since, have been so completely nauseous, it's difficult to function. I've had terrible acid reflux and get the shakes and horrible stomach pain if I don't eat immediately when I feel hungry. My stomach aches constantly and I haven't had a bowel movement for a week. It has been 5 days since I took the last dose.