Hello, Is your 3rd molar is erupting? An x ray would rule out the problem of pain.

Go for xray Only xray can determine what is your problem??

Picture is not giving a proper diagnosis.It would be better if you visit your nearby dentist to get a proper clinical and radiographical examination.

It must be clinically evaluated for the correct diagnosis and treatment planning A radiograph is must for this If you are from Hyderabad consult us we will help you and guide you

U need clinical evaluation along with a radiograph of the area. While u r biting the pain may be due to various reasons. Or may be there is pain during releasing the bite. (In case of any fractures/cracks).

Do you feel pain while chewing only or also while drinking....is there any sensitivity issue...if yes then since how long....is there any gum swelling assosiated with it...??

Your history is not proper for evaluation. From the picture i dont find any major abnormality other than wear off and a filling. Sometimes cavities present on the sides of tooth which can be seen only by x-ray or secondary infection under the filling. Visit a dentist and have a proper check up at the earliest until then for pain you can take the following tablet Tab ketrol DT 1-1-1 ×5days