From state of sensitivity you have come to a state of pain this clearly suggests that tooth nerve is involved a root canal treatment may be required, do not neglect it further,visit a dentist.

Hi..you have a cavity. You need root canal treatment. Regards

Do you have any irregular surface on the side of your teeth?

Hello..sensitivity may be due to cold or hot substances or blow of air but pain during chewing and for a little duration as you said may be due to decay of tooth which can be treated either by filling with cement or root canal treatment depending on the amount of decay which has occured.kindly visit nearby dentist to sort the problem.

Hello you probably would be having a cavity and the treatment whether just a filling or root canal treatment can be confirmed by looking at the xray..do not neglect visit a dentist..the earlier the treatment the better it is..

This does not seem to be a case of sensitivity..... most probably you have a cavity in your tooth which is the reason for the pain continuing for more than a few seconds..... try to avoid home remedies and self medications and visit your dentist soon before the problem aggravates further..... regards...

Pain lingering for a few minutes and not responding to sensitising toothpastes, is an indication of the nerve getting damaged. You should consult your dentist asap and get it treated.