Silver Dollar swimming nose up

hey all,
I wonder if someone could help or point me in the right direction:
I've got a clean 10 gallon tank with a 1/2 dozen fish and 2 silver
dollars. My old one (about 8 years) just started swimming nose up.
It's like his air bladder is messed up. He can't level out. He seems
fine otherwise, but has some red and the edges of his fins. He moves
around and will swim quite a bit, but something is definitely wrong..

We've been using Maracyn-Two for about a week, but no change...

Any Ideas?
--
cm