Need help w/sick fish.
The Problem:
1 YoYo Loach: flashing + large belly
1 Clown Loach: white patch on head
History:
Tank has been clean & disease free since set up in February. I do water changes twice per week. I clean the Eheim 2028 filter on a regular basis.
Started noticing some flashing among shark and yoyo loaches. Noticed yoyo's large belly even tho he hadn't eaten in a while.
Wednesday 6/28 - Added PraziPro thinking I might have some kind of flukes or other parasites that I can not see. Immediately water filled with millions of tiny wriggling wormy things. Figured this was the problem, happy I solved it.
Thursday 6/29 - Fish still flashing a little bit. Thought maybe it just takes a few days to get all the little critters. Prazi bottle says leave 7 days undisturbed.
Friday 6/30 - I notice my largest clown loach (5"?) has a white patch on his head. He hides 24/7 so he might have had it before, and I just didn't notice. I dunno what this white patch is!!! WORRIED!!! Redtail Shark is flashing today also. Also, Yoyo still has a big belly and is still flashing a lot. Thinking the parasite stuff was not the answer.
Saturday 7/1 - Did not touch anything today. Yoyo still flashing a lot. Got a better view of clowns head. White spot almost looks like a scar. It's not extruded from the skin, there are also no "holes" or etc. It's got a couple spidery lines extending from the area, again like a scar. Maybe loach just hit his head real hard on somethin and i never noticed? Or could it be fungal? bacterial? parasitic?
FINAL THOUGHTS:
I don't want to over-medicate the fish. I don't want to give them the wrong medication. I don't want to do nothing and watch them get worse either though. I'm not sure what to do. Should I continue w/another dose of prazi? Should I clean the prazi out and do a maracyn combo? I dunno. Please help!


Should I isolate him? Or continue to treat the whole tank?
Thanks everyone.... appreciate your time!
Tank Stats:
75g tank. 7 Clown Loaches. 3 YoYo Loaches. 10 Tiger Barbs. 8 Cherry Barbs. 1 Redtail Shark. 1 UpsideDown Catfish. No live plants.
79F Temp
6.6-6.8 PH
0ppm Ammonia
0ppm Nitrite
5-10ppm Nitrate
5 dGH
3 dKH
PLEASE HELP MY SICK LOACHES! THANKS!!!