It's not unusual for the sinus infection to spread to your chest--usually it is because of the post nasal drip you get with the sinus infection. It goes down into your chest.
I have a Sinus infection now, also--a bad one--went to the doctor's twice now and am on second round of antibiotics. First antibiotic didn't work well for me, perhaps that was your situation also.
I am sorry you are feeling so rotten and hope you feel better soon!!!