I've had a nose problem for 3 1/2weeks now. i thought it was allergy, no allergy pills helped! i think it may be a sinus infection. what should i do?!

Difficult to tell: In order to help you, you need to be more specific what exactly is your "nose" problem. Is it painful, draining, bleeding, congested, etc. A sinus infection is a nasal and sinus bacterial infection with facial pain/pressure, low grade temperatures, thick discharge, thick post-nasal drip, and can include bad breath and a cough. In your case, you need to see a doctor to sort this out.