Apple snail caught in the intake

I was able to cut the intake and slide him out but it was a slotted intake and i didnt notice it for like a day or 2. When i was getting him off i noticed that the bottom that he use to move on was semi hard like he was trying to devlope a new shell. Now that i got him off he sucked back into the shell and hasnt moved since yesterday. My question is did he start growing a new shell? Will he continue with the new one? How do i make sure he is ok?