I took the executive decision and decided to remove Who (the snail) from the fish bowl. I didn't realize that the scum that was in the bowl wasn't from the algae wafers, but from snail poop
I also did a 100% water change as you all have suggested an Horton (the Betta) seems noticeably happier than when they were together
I did the cup trick and it worked magically. Horton lost only a little color in his scales, but he is A-1. As for Who, he seems happy in his quarter cup filled with water and a small amount of conditioner; I even see his antenna and he is crawling around with much more boldly. I see the spot on his foot though that Horton nipped on and it seems Horton is trying to find who, lol.
Anyway thank you all for your help. I am glad I found this place