If sinusitis lasts 3 weeks but there are only uncontinously mild pain and mild head pressure should be treated with antibiotics? levofloxacin doesn't work (despite 12 days of treatment) and i have also polyps in all sinuses.

See ENT: First you need to ascertain if your problem is indeed from sinusitis and thus an ENT consult would be helpful. Rx options may include (a) abx with oral steroid for several weeks (b) surgical removal of polyps and drainage of sinuses (c) rule aspirin sensitivity which may benefit from aspirin desensitization.

Sinusitis: You need to see an ENT specialist As your polyps may need to be dealt with

Look for the cause: if you have nasal polyps which by your description are probably a lot, these need to be taken care before infection can clear up. sound like you are having sinus problems for a while. Check with ENT and then look into allergy as it is common cause associated with polyps

Sinus: looks like allergic rhinitis. You should take Allegra-D for few days and also Nasal spray like Nasonex (mometasone).