sounds like ich to me...
i could type all about it, but colesea did in another thread so i'll just copy/paste it here:
Ich has three stages in its life cycle. Stage one is a polyp that lives on the gravel, glass, ornaments, and everything else in your tank. This stage is impervious to medications, which is why ich infections become reoccuring in many tanks that are not completely bleached out. This form of the parasite can sometimes stay in hibernation regardless of tank environmental conditions, hatching out when conditions become right again.
Stage two is a free-swimming stages that hatches out of the polyp and swims around looking for a host, aka, the fish. This is the only stage of the life cycle that is affected by medications, which is why most medications require at least a two week treatment period. Frequent water changes during ich treatment also help to remove the free-swimming stage from the water and prevent attachment to fish host.
The third stage is the actually cyst on the fish, which we see as the little white spots. This stage is also impervious to medications, although it can sometimes be combated by changes in osmotic pressure, aka the addition of salt to the environment which will suck water out of the cyst (as well as out of your fish) and cause the cyst to implode, rendering it dead. Once the cysts develop, they fall off the fish and into the sesile stage on your gravel, glass, ornaments, etc. to restart the cycle.
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okay, well all three of those medicines you mentioned should have worked. Also, I'm not good at plecos/catfish/bottom feeders at all, but I do know some medicines can be harmful to them, so before you use another medicine, check it out.
I just a few days ago got over a case of ich after weeks of nothing helping. I used Coppersafe, which can hurt live plants and scaleless fish, but it worked great. I tried three or four different things before and nothing seemed to help. But Coppersafe did.
It stays in the tank for a month to eradicate the parasite thoroughly, which is important because you do not want to discontinue the treatment before it is really gone. Sometimes people mistake the stage of when the ich falls off for it being gone and stop treatment. Just keep trying and keep some salt in there and raise the temp to 82 ish or higher, if you're fish can stand it.
good luck.