I had a sore throat on 12/27 which developed into stuff going down the back of my throat for about a week, then became bronchitis (xrays, all tests neg). No malaise, no breathing problems until nonproductive cough. Took 1 of 1st 2 of zithromax (generic) and felt weird in stomach, tingling of nose,face. Feared heart palp & dizziness so switched to amoxicillin 500. Bad cramps yesterday and nausea so couldn t take amox ( had the zith Fri PM). Better this am but afraid to take even amox at 500 because I had probs in past (have tolerated 250). All resp. symptoms feel completely gone, gut still burning. Loose stools (had about 7 years of sensitive bowel problems about 10 yrs ago, had to stop work) Finally was ok. Do I have to complete antibiotics? Had namebrand zith in past with no probs. What % risk of mersa, etc if I don t? 63y.o. female.