Hello Please visit a dentist and get a x ray done so that you can check if the decay hasn’t reached pulp

tooth filling is gone that means there is cavity  because  of which inner portion of tooth dentine is exposed . it gives pain . after refilling  your pain might reduce. . as filling is gone 3 months back root canal treatment  may be needed if pain remains after repeat  filling.

If you would have filled the cavity soon when it came off you wouldn't have experienced these complications Now that you already have pain while chewing or due to food lodgement... I would advise you to visit a dentist and get a x-ray done. X-ray will give a better picture for the dentist to understand and suggest you accordingly If the cavity has reached pulp root canal treatment is the option.

Rct needed aftr an IOPA

Get an X-ray done. Clinical examination and X-ray is required to advise you. If the decay has not infected the pulp then a filling will do else an RCT and capping may be required