Go for the dentist. Advice  X-ray.may be there is some infection in the roots of the tooth... Rct and again  bridge.

There are three possible reasons for that 1. You can have secondary decay on the tooth which was capped before (assuming that root canal was done) 2. There can be infection in the roots due to some residual microorganism. 3. You have some gum infection due to food lodgeing between your tooth and gums. This can be confirmed with X Ray and clinic visit. Kindly visit your nearest dentist.

If the bridge came out, you must get a dental check up. Your symptoms indicate one of the teeth on that side may have pulpitis and require a root canal treatment.