Sick Ram

Hey guys,

It's been weeks - everything has been going well, the ich was cured,
the plants are growing like crazy...

A few days ago I noticed my female Blue Ram (Priscilla) at the top of
the tank breathing hard. Elvis wasn't chasing her and now completely
ignores her. She's not eating, she's looking thinner and a little
sunken in the abdomen and it seems like she's trying to get air from
above the water line. I don't think she's going to live long if I
don't figure this out...

All the other fish are thriving.

37 gallon heavily planted
Ammonia - 0
Nitrite - 0
Nitrate - 0
Ph - 7.6

Co2 stopped working a few weeks ago - I think I sprung a leak in the
line and I've been too busy to buy more. I have some algae but it's not
bothering the other fish and it's not terrible.

Two blue rams
Two young angels
15 Cardinals
4 otos (lost one in the ich terror)

Thoughts?