I had a back tooth removed over two months ago the wound is still open and i'm in constant pain my dentist recommends we wait till it heals?

2nd opinion : There could be several reasons for this but if you are still in that much pain I would suggest a 2nd opinion from another dentist (preferably an oral surgeon). There is a wide variation on how long healing takes especially with some medical conditions but it is best to be safe, especially if you are still uncomfortable.

Seek second opinion: Did the dentist state that you have a dry socket, and were you treated for that? Smoking is not advised, it delays healing. See your dentist or go for a second opinion if the pain is constant and the area is not healed. Many systemic medical issues can retard healing in addition.

Oral Surgeon ASAP: The initial healing period of gums usually takes about 2-3 weeks. The major signs of infection are pain, heat, swelling, and redness. I think you need of see an oral surgeon ASAP for an x-ray and curettage of the area to stimulate some new healing. Do not delay.