What Does Screeching Noise In Ears Indicate?

I have had screeching noise in my ears for 4 months with sinus congestion and ear pressure. Dr. Says my ears are full of fluid and my sinuses raw so prescribed Clindamycin. This is my 4th day of meds and the ear noise is getting even worse. Can the Clinamycin be making it worse? I ask because its Sunday and I can't reach my doc. I wonder if I should stop meds.