I'm really glad you went to the ER and they figured out what was going on. I hope you start feeling better quickly.
I actually went to the ER today because it wasn't any better. I just posted another question about it. I have fluid and inflamation around my heart. The ER doc called my surgeon and they put me on ibuprofen and colcrys. Thanks for the comment becasue when I read it, it pretty much confirmed to me that I should go back to the dr. Hopefully I can get past this inflamation/fluid and get back to a normal life soon.
I am not a doctor but I can not imagine why your shoulder would hurt when you breathe with a sinus infection. If it's still bothering you I would go to ER.
I did and he seemed to agree with the sinus infection. My shoulder is still hurting some today I might go to the ER here shortly. My surgeon is about 90 miles away.
If I were you I would contact the doctor that did your surgery asap. I would not wait until Monday, there is someone on call I am sure.