Root Canal Gum still swelling

I had a root canal on a upper back molar about a year ago.  It was never completed correctly since I still am having swelling on the gum.  The dentist had a hard time finding all the roots he said.  It does not hurt.  He gave me antibiotics a few weeks ago but the swelling is back again.  How long can I let this go like this with out harmful effects on me?  It never did hurt even before the root canal.  I can't afford another root canal and I don't want another tooth pulled.  Help me decide what to do please.

[Sam Delfino]

Hi,
How long you can wait? It may already be too late! A year of infection on this tooth, and swelling, that means lost of bone getting destroyed. If you do not mind losing this tooth, and possibly damaging the bone around other teeth, keep it the same way. If you want to save the other teeth, remove it as soon as possible and then you have to deal with the issues related to bone loss and teeth shifting or tilting or erupting up, if you want to do the best for yourself, then have the root canal redone, IF it has the right prognosis. I would see a highly qualified endodontist if I were you. http://www.top3dentists.com/pages/endodontics