Mouth Ulcer

I have had an ulcer in my mouth located under the back, bottom, right molar for 3 weeks.  I have been to a dentist twice and my physician once.  It has gotten better, but a hard ‘thing’ was in the middle.  I reurned to the dentist and he said that was my jawbone exposed.  He is giving me 2 weeks for the gum to grow over it or he wants me to go to an oral surgeon, who will shave the necrotic bone off to expose good bone. I would like to avoid this if I could.  Two days before it appeared, I was hit in the side of my head by an extremely hard spike. 

Have you ever had an ulcer eat to the bone in a patient?

Should I see a periodontist instead of an oral surgeon.  The tooth above the ulcer has had a root canal.  That tooth doesn’t hurt, but the gum surrounding it is EXTREMELY tender and it hurts to eat.