Sneezing And Running Nose. Doctor Told Its Sinus Infection And Gave Antibiotics Which Did Not Help. Advice

Hi Doctor,

I am a 35 year old female, been suffering from sneezing & nose producing too much mucus for the past 6 months, had to blow my nose every half an hour. went to the doctor & told me its sinus infection & he gave me antibiotics but didnt help, but i am suspecting post nasal drip, because of the sympoms I read about online.

Then went to the pharmacy & the lady said she is suspecting it could be allergy & gave me allergex tablets, I started taking them 2 days & my mucus has turned yellow, is it normal? can you help, what do I have to take? I have tried so many thing, sinucon, sinutab, sinastats, sinus max, sinu end, nasal sprays, I even sniffed ginger powder to that extend.