If the pain is something new you should have it checked by your dentist. Maybe something that should not be ignored. If that is O.K. the the route I took may prove helpful. I always suffered with this and finally had my dentist file my front lower teeth even ( I too had one that was higher than the other). That seemed to help and certainly made the embouchure even which I percieve to be good thing. However, this was not enough help. I got a trick from an older sax player who would use cigarette papers folded and laid on top of the teeth to cushion the pressure. He did this on long playing sessions. The only problem is there are possible health issues due to the stuff they use to process the papers. Finally I went to a dentist who was also a player (Clarinet). He had studied everything that the American dental Inst. or whatever it is published and applied himself to assiting horn players. He does a lot of dental modification for trumpet etc players but for reed players he makes a mold of the lower front teeth and uses it to make a guard of some sort of plastic that fits over the teeth. This thing is the greatest thing that I have ever seen and eliminates all pain and you do not ever know it is there!!! The cost was 90 dollars and was the best money I ever spent. I hope this helps.