What Causes Recurring Tooth Infection And Swollen Lymph Nodes?

I have been being treated for a infection in my tooth for 2 years, followed by a root canal then a surgery after the root canal didnt work. I have taken antiobiotics on and off for 2 years and the problem goes away afer abou 2 rounds then comes back. I have sinus pressure on that same side. After having the dental surgery I still have the same problem and dentist said the tooth healed correctly and the bone grew back like it should. They have referred me to a head, nose and throat dr. my glads tend to swell on that same side. what could this be. i have been told that my sinuses are very deep