Nerite Snail Parasite?

Hello,
I got a nerite snail about 5 days ago. He is in a 5 gallon heated, filtered tank with one betta. I got him to hopefully clean some algae and to ad another creature to the tank. My betta bugged him the first day but now ignores him. The first day the nerite was active and moving, cruising along the substrate and glass. The next day he stopped moving much at all, and now just sits on the glass and does nothing. I haven't seen him eat the last few days. Weird stringy things come out of him every day, so I'm trying to figure out if its stress or a parasite. Advice on either would be appreciated.
Pics attatched.

 

This is how Nerite Snails sleep. They also go to the surface for air occasionally. They will do this for long periods of time. The stringy thing is most likely poop but an image of it would be helpful.

 

The stringy thing is visible in the picture. It's the yellowish string coiled to the lower right of the snail. Each day something like that comes out of him.

 

Hmmmnn. To me it looks like a plant root. But if it comes out of him... Keep a close eye on him. He seems to be acting fine. Maybe he ate something weird. Tell us if anything happens.

 

I have a small nerite snail, two in fact. And this is my first time keeping them. I have always noticed small stringy thing coming out from their shell, at first I thought it was a parasitic worm, but then I realize that it was their eyestalk(for mine at least). Small nerite snails are so tiny that, their eyestalks really look like detritus worm/parasitic worm to me