Chronic dental fistula for 1yr caused by tooth extraction, hole in sinus closed now, no sinus symptoms. 2 failed ops. still pus draining. any ideas?

Infection present: Neutrophils or certain white blood cells are the first line of defense against infection. This makes up most of the pus you see. You most likely still have infection present. Whether it is from dying bone or residual tooth root, or a consistent draining from the sinus. I wouldn't be able to tell with out an x-ray. If you have pus draining it could be from another tooth.

Still Infected: You still have an infection there somewhere (pus is your indicator). Change your Oral Surgeon to somebody with time experience. They need to find the site of infection, get drainage, close to healing, place you on Peridex soaking for 2-3 times a day until the surgical site closes. Peridex disables bacteria.