There are 2 bumblebee snails and 2 blue legged hermits, all added at the same timeThe white poop is definitely a sign of internal worms. Since he’s eating I’d suggest you medicate his food using the info here: scroll to the green text.
for the ammonia I would buy bottled bacteria: fritz turbo start, dr time one and only or bio spira.
the face: I can’t tell. Could be brook or an infection. Is there any other livestock in the tank besides the clowns?