Hi! i am currently on the z-pack and prednisone for a sinus infection. now i think i might have strep. is that possible w/being on an antibiotic?

Possible: But it is more likely that you have a viral sore throat which antibiotics will not help. If it is not better in a few days or it gets worse and you have vomiting, neck stiffness or other worsening symptoms see your doctor again.

Z-pack: would take care of the strep throat if you do have it, sore throat can be due to viral infection, or other throat irritants, the antibiotic won't help if this is the case, salt water gargles and pain killers would help, if no improvement, see your doctor again, good luck