Going by the description that you have mentioned it seems that you are suffering from either of these two problems. Either any of your tooth is infected along with the gums surrounding it causing the pain to radiate to the jaw joint in front of the ear as well as involving the muscles causing restricted mouth opening; or the other option is that you have some problem in the jaw joint only which is causing the discomfort. Please understand that these suggestions are based only on the description that we have received without a look at the clinical picture and without performing a proper clinical examination or evaluation of the xrays of the area. The most prudent step would be to visit a dentist as soon as possible for a proper clinical examination so that the right treatment can be instituted after the right diagnosis has been established. Regards.