Skipping beats and pain

I am a 46 y.o. cauc. male whom received a double CABG 15 months ago.  I had a 98% blockage in my left main.  I did rather well the first year post-CABG.  Now I have been to the ER for the same thing 3 times.  A nuclear stress shows no abnormalitys.  My heart is skipping as many as 15 times in one minute and at other times none.  Most of the time it skips.  There is some pressure and a lot of "pinching" type pain over the heart when the skips begin and continue.  A nitro tab under the tongue will help some with the pain but will not help the irregular beats.  My cardio doc says that it is nothing to worry about, but after having a CABG and now having some of the same syptoms (symptoms) pre-CABG begins, I can not help but worry.  It hurts.  I take Topral, HPB meds and 16 other meds.  I feel like a very old man most of the time.  My question....should I worry about the pain and beats.  I go back to the doc in 2 weeks.  They can't see me any earlier unless it is a 911 call.  Help please.