Sorry I was gone, I'll try to lend some sanity here.
Your water parameters do seem to be fine. If you have been cycled and steady for several months, then we need to look elsewhere. I try to keep my nitrates below 20ppm for safety. You can have nitrate poisoning at as low as 40ppm, but that isn't the norm.
I don't think that it is your water parameters at work here. I believe that it could be an internal infection or parasite. But there are other possibilites as well.
It could also be heavy metal posioning, vapor poisoning from suspended chemicals in the air, shimmies, constipation, swim bladder disease, O2 deprivation, CO2 poisoning or a water quality issue at the tap. You also need to make sure that you are properly conditioning your water before you add it to the tank.
To get a better handle on your problem I need you to define some things for me first.
1) When you say "acting funny" or "swimming funny" can you be more specific as to how they are behaving?
2) Describe anything else that you can about the conditions or the tank that you can think of, even if it seems inconsequential.