This is the fifth day on avelox q d for sinus inf. Should I still feel bad?

OTC Meds as well. Abx, help fight the infection, but sometimes doesn't make one feel better right away. I have my patients also use Mucinex (guaifenesin) to loosen the mucus as well as saltwater rinse. This combination works well for my sinus patients along with the antibiotic.
No. You should be starting to feel better by now. Adding nasal saline spray and topical nasal decongestant spray like afrin for 2 to 3 days may help speed up your recovery. If that doesn't fix it consider having a nasal culture done. A lot of bacteria are resistant nowadays.