Why sore throat persist despite taking antibiotic courses?

Hello doctor,

I am a 27 year old lady. I started having a sore throat two months back. I just thought it was a flu coming. But then, when I noticed that it had been on for two weeks, I decided to take Amoxicillin. I took it but did not finish the course on the last day. I had traveled and forgotten them at home. The sore throat went away but came back a few days later. I took another full course of Amoxicillin and during the course, the sore throat went away. I finished the full course but a few days later, the sore throat came back again. I went to the clinic and the nurse noticed that my throat was inflamed and prescribed Erythromycin. I took it but the sore throat kept on coming back. The nurse then prescribed Ciprofloxacin. I took the full course but still the sore throat did not go away. When I went back to the clinic, the nurse said it was no longer inflamed but I could feel it, but only that the discomfort seemed to be going deep down the throat. It is like each day I can feel it is moving down. It is not a very painful sore throat. I do not take any painkillers. My body temperature and blood pressure are normal and have been normal throughout the period. Right now, I can feel discomfort in my upper part of the chest. Another thing is that the first episode of sore throat occured after I visited my sister who from time to time gets swollen glands (below the ear). What could it be and how can I get well again?