I Have Been To The Dentist With An Aching Lower

I have been to the dentist with an aching lower back tooth. On examination including x ray nothing unusual was seen. I was prescribed antibiotics but they had no effect. The pain is a dull ache which increases spasmodically from dull to severe when I feel it throb. I cannot sleep when this is throbbing. A cold contact or hot contact will bring it on immediately . Sometimes it seems the pain is in both upper and lower jaws. I do suffer from peripheral neuropathy following chemo fFor a colon cancer 18 months ago. My dentist said if the antibiotics did not work she may have to refer me. What could be the problem. I cannot keep taking heavy doses of paracetamol.