I've followed the exercises in this video, & within 2 days my elbow pain has been hugely reduced; both elbows hurt on the inside, at the point where a rounded bone protrudes -at first I thought it was from clenching the guitar with the right arm, but when the left elbow also began hurting, I searched the internet for help (!) with very good results!
I hope this works for you, too. . . .