Hey there. You're explaining pretty normal stuff that happens to everyone. You can still use the power armor but there are some benefits like sprinting maybe that don't work. You'll want to take the deathclaw down using the VATS (special weapon hits, slow motion) with running and dodging. Best part about fallout is you can just do something else and explore to get more experience and access to better weapons. Save often so you can go back to a prior save if you happen to kill the wrong person or get killed.