I think the elbow should be straight, just not locked out. Reason being, when someone shoots with a bent elbow, there is no way to be absolutely sure the elbow is bent exactly the same on each shot. So, the draw length - or anchor point - will vary slightly on each shot, which can easily cause inconsistent shot placement. I've seen some guys that can shoot great with a bent elbow. On the other hand, I've seen many more bent elbow guys who couldn't hit the broad side of the barn from inside the barn.

But straight or bent elbow isn't the root cause of your problem. I have to echo the number 1 suspicion that your bow's draw length is too long for you. If you weren't having problems before you had the draw length changed and now you are, that kinda falls under the heading of... DUH! Change it back the way it was.

Another good possibility is that the string and cables have elongated and aren't under the proper tension. That will let the string tatoo your forearm. Check your axle to axle length and brace height. If the a-to-a length is longer than spec or the brace height shorter than spec, then get the bow back to the dealer and get them to twist everything up and make it right.

Are you using a metal nock loop? Those metal loops are heavy enough to make the string snap way forward of where they would normally stop and cause you to get string rash. On top of that, the metal loops wear strings out very quickly and cause them to break. They will ruin the jaws of release aids. They cut your arrow speed. I can't think of anything good to say about metal loops. If that's what you've got, definitely get rid of it and switch to a string loop.