welcome to fishlore!!!
Could the loach have gotten stuck at some point, into a decoration or something?
as far as the tan stuff, can you let us know how long the tanks been running? what size the tank is? whats in the tank with the loach? and whats the
ammonia, nitrites, and nitrates of the tank? If you go to my settings, and fill in the aquarium info, it helps us try to help you more without all the questions ...it could be diatoms (new tank algae) or even overfeeding ....
we have allot of loach members that can help more, but getting the answer to these questions, will help ...