help!?

My oral surgeon told me I have TMj. but he also told me that the right disc in my jaw joint was slipping in and out everytime I open and close my mouth and on the left side my disc was stuck he prescribed a night gaurd I wore it for 3 months and the whole 3 months my jaw was locked closed. I have severe pain, hard time eating has lost from 120 to 102 lbs. since May because of this condition.  The last time I went to him he told me I needed surgery because the night gaurd was not helping. Do I need a second opoion or should I just go ahead a have the surgery?????? Help????