sick betta-fin rot and ich?

Question
I treated my male betta for finrot using bettafix which was recommended by pet store. I used it for seven days as recommended. I did a partial-20% water change after treatment. Now the fin rot is back and he is developing holes in his fins. Also, I see one scale is raised and white, almost like a grain of salt. Could it be ich? I only see one large grain, so should I treat for itch and fin rot. Also, all of my problems started when I switched to a cheaper filter. I have been battling a lot of debris in the tank since the filter change and I cut down on my feeding by half(he gets 3 pellets/day). I suction the debris out by a siphon once per week and usually  replace 20% of the water. What am I doing wrong. All chemistry looks good except nitrates are a little high, but that is due to my tap water which I tested. Should I do a complete cleanup of the tank before medical treatment and should I remove the filter? Everything just seems to be spiraling out of control.

Answer
Hi Linda,
It seems as though this all stems from changing to a new filter. This is entirely possible, since a lot of your beneficial bacteria usually lives in your filter. When you suddenly take it out, you deplete your biological filter greatly, and this can be detrimental to the tank. If you haven't had the filter out for too long, or thrown it away, add it back to your tank alongside your other filter for at least two weeks to allow more bacteria to grow in your new filter while still housing bacteria in your old one.
If you can't do this, add some bacteria supplement to your tank along with some slime coat replacements, keep up on your water changes, and find a way to get rid of those nitrates as they are toxic to your fish.