Crewdroog: get one of those gels or sprays that has lidocaine in it. it's a local anesthetic and will help a lot. Also, you can take Ibuprofen; it is an anti-inflammatory (unlike tylenol), so besides taking away some pain, it will reduce the swelling. Cool baths and compresses will help as well.
This, absolutely. The lidocaine+aloe gel is the best. Apply liberally. Buy zinc oxide cream for your face for the rest of band camp, especially for your nose. It is very thick but is the best blocker out there, and one of the safest.
Sunglasses, not with tiny hipster lenses, but large lenses that cover your eyes and a lot of the area around them. Your eyeballs and lips can also get sunburned. Protect them.
A hat---and if your band director wants to complain, go straight to the doctor and get a medical note. You've already gotten sunburnt and don't need extra exposure.