K30: Dwarf Frog Dead??

Hi K30 and other African dwarf frogs owners,

Sort of OT here but I've got a situation with one of my dwarf frogs and
wanted to ask you a question as I remember you have/had these critters too.
One of mine is +/-3yrs old. Yesterday he started wanting to be at top of
tank, hanging onto the filter, floating near surface. He has never done that
before. He is not bloated as in dropsey. Today he was on his back at bottom
and I have put him in a separate jar 1/2 filled. He doesn't move but if I
remove him from jar, his front limbs will slightly twitch. My question is,
how long have your dwarf frogs lived in your experience? Also, I'm not sure
if mine might actually be dead as he is not coming up for air. Any opinions
from anyone keeping dwarf frogs are appreciated. The tank is 2 gal eclipse
with filter, open top for air, 2 dwarf frogs + 1 cory. I did clean and
replace the water this morning after discovering the frog but water quality
was normal. Note that I feed them every other day, a small amount of frozen
bloodworms or brine shrimp. The other frog is fat and sassy. This one has
always been thin but healthy until now.

Thanks in Advance.
Sandra