paradise after treatment

Well, my best guess was internal parasites so day before I did a 50% water change, dosed the window tank with levamisole, covered it against light for 24 hours, then a huge 75% water change next day. When it was down so low the water level was barely height of the fishes' bodies- they didn't like that- but I had new water on hand to quick start refilling again. I gravel vacc'd as well as I could around the plants with the tiny one (airline and medicine syringe). This pic from the 50% wc I did just before dosing the meds- Laddie is the blur on the left.

Perry is on the right here- I patched two photos together so half the crinum is missing and the light on surface doesn't match- but you can see how healthy all the water spangles have grown in!

But- nothing has changed. Laddie's fin is all clear, now- I'm sure the huge water changes helped clear up that little problem. He darts around eager and interested in everything. Perry- as in the above picture- sits looking miserable just at surface or on substrate, in the shelter of a plant. He only eats half the bites I offer. I still don't know if this is virus, parasite, or just behavioral- is he so depressed and intimidated by Laddie next door . . . Well, I'm going to let him rest a few days, then treat the tank with metronidazole, and repeat the dose of levamisole in a few weeks- just in case the stringy poo I saw really was from a parasite load- but somehow I feel like it won't help.