Biting my mouth!

Please help. This is my first visit to the forum & hope someone can understand what on earth is happening to me. I have had R&R MS for many years & with the help of Rebif & several other meds I am very lucky to be reeeally well. But for some reason lately I have started to seriously bite down on the inside of my mouth & lips whenever I eat. Has anyone else experienced this? It is very painful! Do you I am having another relapse??