These things (accidentally biting on some small stone) is very common. Your teeth are not made to tolerate such excessive force. So a small injury can occur leading to reversible pain ,specially while chewing, for some time. But in case you have continuous pain, consider something major has happened including tooth fracture. In the case where it is indeed fractured you can self check by pressing or trying to move the specific tooth. In a larger and general view, If you cannot pinpoint one tooth, nothing major happened.

You seem to have decay in tooth which has caused a hole and decay has reached the pulp which is causing pain.need wither root canal treatment or extraction of tooth depending on severity of decay and tooth structure loss.