It sounds to me likely you likely have a bad viral infection, possibly the flu. True bacterial sinus infections almost always get better within 2 days of starting an antibiotic course. You have had three courses of appropriate antibiotics for a bacterial sinus infection without compete relief. If you really had a bacterial sinus infection you would be better by now. This tells me that you almost certainly did not have one and that your infection is viral that does not get better with antibiotics. The symptoms of achy joints, mild headache
, post nasal drip, sinus pain, and mild upset stomach are classic for a nasty viral syndrome. Some cases of the flu can cause this combination or sometimes a really bad upper respiratory tract infection. Unfortunately, there is no cure so you will probably have to wait it out.
I suggest that you schedule an appointment with your primary care physician
to discuss this issue further. Make sure to be ready to describe your symptoms in detail to your doctor
. There are medications that your doctor can prescribe you that can really help with your symptoms and make it so you can function during the day while you fight this infection. Good luck.