You're welcome, I hope they get back to you soon and that it helps! Please keep us updated on progress, rooting for the poor little dude
@Byron @Colin_T sorry to tag you guys, hope you don't mind, but concerned for this poor little rescued fish, and others suggest you guys know a lot about fish health!
OP, most fish get treated for worms without being diagnosed via microscope, so it might not be crucial! But if anyone can discover something through them, I believe the folks on WWM can. It might be a case of treating him with a general wormer, keeping him in quarantine and monitoring him, and seeing if he picks up and fills out. Then if he didn't pick up and still seemed wormy, trying other treatments. But any type of medicating, even adding salt to a freshwater tank for ich or fungus, causes stress on the fish and can weaken them. Which is why I and others are suggesting to keep him in quarantine and hold off on throwing any chemical treatments at him until someone with more knowledge can suggest the best things to try first. We don't want to kill him by trying to treat something he may not even have, ya know?
How is he doing otherwise? Eating and swimming well? Active or lethargic? Any fin clamping?