I Have Been Having A Lot Of Sinus Drainage Going

I have been having a lot of sinus drainage going down my throat and my ears are stopped up with fluid and for the last three days I have developed a hacking cough, and my throat is sore, about 4 weeks ago I went to the doctor and was given antibiotics but I have taken all of them at 3 times a day and I am taking an antihistamine but nothing is giving me any relief. Could it be my sinuses causing this problem and what do I do?