Pain in the end of throat. Or syrup.

M 26 yr old , I used to smoke 5-6 yr cigarette in a day bt from last 2 month quit that. I never faced any such type of issues when I used to smoke cigrt. Bt 2 weeks before there was brown blood type something I found in my cough that too fr 2 days only nd very little stains when I was cleaning my throat roughly. I went to ENT specialist bt he sd its all clear no need to worry nd he prescribed me gargle syrup now my mouth is all clear . Bt from yesterday m feeling pain in my back nd lower part of throat whenever I used to swallow something . Nd m having burning sensation . Nd whenever I eat acidic foods it happen very frequently. This happens wd my dad . Also m having acidity problem Plz suggest me some tablet or syrup .