Can Abscess In Sinus Cavity Cause Danger?

When i was active in my addiction i neglected my teeth, I had the upper left last molar in the back break and lived for at least 3 years with it broken off horizonatally at the gumline and finally had it pulled in treatment but not before it affected the tooth in front of it, After months of pain that increased daily i finally had it pulled as i was pretty sure i had an absess because i had a huge lump on my gums right about they eye or canine tooth. I had to take 2 rounds of antiobiotics in order for them to pull it and that was a little more than 4 months ago, but the lump never went away, it doesnt necessarily hurt but there is alot of pressure and in the last two months it seems as if i get every cold, infection, etc known to man, ii am worried that the absess is in my sinus cavity and i dont know what to do