Shell issues

[arosenbaum]

Hey everyone! I have 2 small-ish crabs that I've had for about 2 months now. This is my second time with crabs, and I've felt a lot more confident about their care now. Both of my crabs unfortunately came in painted shells, and I've given them plenty of natural shells to change into. One of them changed about 2 weeks ago. The other one has been holding out, until tonight. I recently created a shell shop in my crabitat, and they both seem to really enjoy hanging out up there, even if not to change shells. So I was watching them for a while tonight (they are hilarious to watch) and noticed the one that hasn't changed (I call him Red) really messing with one of the shells. I wanted to see if he'd finally change shells. He did, and it was cool to watch because I've never seen it before. After he changed, though, I took out the painted shell because I don't want them deciding to use those again. After I took it out, he seemed a little panicked, as if he was planning on going back into that one. I don't know what to do, because I don't want them to go back into them, but I don't want him to hate his shell. It does seem a little big on him. After a couple minutes, he switched into another shell I have in there, but quickly switched back to the original shell he'd switched into. Also, I might need to move into the emergency forum, because when I pulled his old painted shell out, there was a teeny tiny bug moving on it. I quickly sealed the shell in a ziplock in case there were more. I bathed my crabs both before I put them in my crabitat (I know it's a controversial issue, but I decided to do it just the one time after I brought them home. I also recently did a deep clean of my tank (changed the substrate, boiled everything in boiling sea salt water, etc. because I had a mushroom (I know, ewww) growing in the tank!) Anyway, I am more than willing to fill out the emergency form for either issue if needed, just lmk. (Sorry that was so long)

[arosenbaum]

Update: shortly after posting this, Red did change into a slightly smaller shell, and seems okay with it. We will see. I hope I didn't stress him too much.