Did things change when you switched arrows, or when you sped up the bow? Simply speeding up the bow normally doesn't cause that much trouble, especially at the speeds you are talking about, but it could change the spine of the arrow required. However changing arrows, messing with the weight on the string and that sort of stuff will profoundly mess with how things work.

There is whole list of things that could be wrong now. Did you re tune the bow? Are your arrows good? Are they the correct spine for your bow? You can't just slap new arrows on and expect everything to work perfect. Especially when going from aluminums to carbons. You said you are shooting a helical fletch, are you sure you are not getting fetching contact? Even with a drop away you can have fletching contact, they need to be checked and set up properly.

We would need to know a lot more information before we could even start guessing what your problem is.

Paul