DON'T wait until you get a test kit.
DO A WATER CHANGE!!!!! Do it now!!! :D
Yup, get off the computer, and grab a bucket and some dechlor! :P
30% if you have done a water change in the last month.
50% if you have done a water change in the last two weeks.
80% or more if you have done a water change in the past week.
The different percentages are to ensure that you don't shock your fish with a huge pH drop while still giving them the benefit of a water change.
Just about 95% of all lethargy and bloating problems that arise with tanks such as yours...(fish too large for the tank that have been in these conditions for 6 months or more) can be alleviated with multiple water changes and RELIGIOUS water testing for nitrATE levels thereafter.
As for the bloating. Stop feeding for a couple of days or even longer.
GET A TEST KIT.
Yup. Get in the car, go get one now, tell your spouse you're off to get a pack of smokes or the new PS3 and go grab a test kit. No strips though. You need the liquid nitrate test in the WORST way.