I have had bppv once before. Lasted about 2 weeks. Didn’t have any sinus issues at that time. However, sinus issues can cause dizziness as can tight neck and shoulder muscles. Did the dr check you for bvvp? They can do that- I had massive spinning and, because I didn’t know what it was, went to the dr. They checked me for it. Had never heard of it before. Since you are confirmed to have some bad sinus issues and you are taking the antibiotics and the dizziness is clearing up, though not totally gone, it sounds like it might likely be the sinus issues. And anxiety will increase the effects of dizziness as well so if you are constantly worried about it and checking for it, it will be more likely that you will experience it. Bvvp is harmless, just annoying. So regardless of it being that or your sinuses, it’s more an annoyance than catastrophic. Hope this helps.