What is the best combination?

I'm 17 years old and my doctor found paulups (i think that's how you spell it, ) in my nose and it's causing a mucus build-up in my nasal cavity. None of the anti-biotics I've been using has lasted for very long (I've had this for about two years now) and I'm wondering if there's any over-the-counter (safe) combinations I can use for my upcoming Marching Band Competition (It's our district competition and I'm the lead trumpet with two solos) so I can breathe.
Any advice would be greatly appreciated!

Over the counter antihistamines (such as those found in cold and allergy medications) can help clear the congestion caused by nasal polyps. Do keep in mind that antihistamines can make you drowsy. Also ask your doctor for prescription corticosteroid spray which can shrink the polyps.

Thanks for the input! I should've stated in my original post that my doctor has also prescribed four or five corticosteriod sprays specifically for polyps (Thanks for the correct spelling!) and those actually make it worse in the long run. So I'm basically back to square one with half the board untouchable. How drowsy can they make me though? Will I fall asleep on the field?!?!?! Just kidding, but seriously, how bad is the drowsiness in these antihistamines?

It is recommended that you take the antihistamine only before bed time. In fact, many people take antihistamine as a sleep aid. That way the side effect would not interfere with your day time performance. The positive drug effect should last through the following day without the drowsiness side effect.