Thank you for asking the query.
You have not mentioned how long back you completed the ofloxacin + Cefexime combination.
It is safe to take Azithromycin, since it is an unrelated antibiotic, but probably you might not need it. Try general measures, steam inhalation and pain medicines. If you Doctor suggests an antibiotic please go ahead with it.
In order to give you further infomation I would like to know how long back you too Cefexime + Ofloxacin and whether you developed the sinus infection, while you were taking the antibiotics.
I would also like to know the symptoms you are having.