If you have checked your peep and nock point It sounds like you have string or cable creep not stretch. If it is creep you may need new strings and cables. I suggest Winners Choice or Vapor Trail. They have very little stretch and no creep. Have you checked your draw length and poundage. Longer cables will drop poundage and longer string will make your draw longer. If you have string stretch that means it will stretch and stop then you can twist the string and it should stay. If you have creep witch it sounds like you do it will not stop. Your loss of speed my be from the cables changing.Also your nock point will change when your string does. Sorry Iam jumping around.
Alright, I think I may have figured out how to post on here. Sorry about the blank.
After checking to assure that no other parts have moved on your bow, think about a new string and cable. I can point you to a very good set. I would go with R.W. custom strings. E-mail me for the phone number as I don't know if I'm allowed to put it on here.
Eddie