Im still having lots of infections despite raising my vitamin C to even 1500mg a day (Maybe too quickly) It doesnt do anything, plus it gives me bad GI problems

My dental infection came back, i have the flu for over a week and the doctor said i have a sinus/respiratory infection.

They wanted to give me Chlarithromycin so i said no ways, so now its between Clindamycin and Aerithromycin.... Anyone have an opinion on this as i need an answer. I am dead scared of antibiotics as I havent had good experiences with them. Please can someone help me.