Erbs palsy since birth. 22 now. loosing motion in hand slowly, arm locking up more, numbness more. more pain. what do i do!? splint/brace? surgery?

Never too late: Erb's affects the upper brachial plexus, and your hand involves lower plexus, so this is new superimposed on the prior. The symptoms raise concern that a complex regional pain syndrome may be evolving, and this needs to be addressed asap. The therapy can wait, as the diagnosis must precede. Believe, your best bet is to see a physiatrist initially and perhaps other specialists later.

Sounds like new prob: Really need a diagnosis as your description is one of a superimposed newer problem. Maybe complex regional pain syndrome. Seek out a physiatrist and get started.