I had the same thing in my last pregnancy. It is carpal tunnel. I wore the brace things also at night and it helped. Surprisingly it did go away like a week after I delivered. Try to go by the braces. I think my doctor also said to elevate them at night but I could never get comfortable but would do it when possible during the day.
I haven't had anything in my arms but my fingertips have been numb almost constantly for at least a month, and I'm also at 25 weeks. I also had some passing carpal tunnel-like pain when it started. My doc recommended wrist splints at night so I got cheap Ace velcro wraps and they seem to be working. I still have numbness in my right thumb/forefinger almost all the time but it's pretty mild. You might want to try an elbow brace to immobilize yiur arm at night - mention it to your doc and see what they say.
Carpal tunnel symptoms are very common due to fluid changes/swelling; I understand they go away after birth for most people. I also have sore tendons in my foot in the morning but it goes away quickly.