My son, 13, was just diagnosed with Lyme's disease. Doc. was pretty sure the rash on his arm was a result of tick. He started my son on a 20 day antibiotic regimen of doxyclc 100 mg tabs. My son is having a hard time with the meds, upsets his stomach and this morning he was complaining of a pain in his stomach. Is this all normal? He doesn't want to drink his 2 glasses of water with the pill. Will he have an long lasting affects of this disease, he's so young.