Right one molar pain when clenched.

Dear Doctor, I have a problem with my right middle molar which is alone because rest of the two have been extracted a long time ago (4 years) and no implant. I went to a Dentist and he did OPG and said there is no infection and everything seems alright. He said there is no problem in the OPG. I have the following symptoms: 1. Pain in that tooth and it's gum when applying pressure from upper jaw. 2. It feels sensitive only on pressure but not on cold or hot food. 3. This gum always feels little sore. 3. Pain in right side of tongue. Sometimes it's burning pain. 4. There are teeth marks on my tongue in the morning only. Although this is not an unbearable pain but it's discomforting, If there is no problem in the OPG, then what is causing this pain.