I am confused as to why this is on an abortion forum??
Still the answer to your question is yes there are over the counter preparations to stop diarrhoea. But it sounds like the worst has passed (excuse the pun!!). Try just jhaving clear fluids (no dairy whatsoever) for 24 hours then gradually reintroducing simple basic foods like boiled rice, potato, toast etc & see how you go.
However, if the diarrhoea continues or if there's any chance it may be to do with medication, or if your weight is very low I would suggest seeing a dr just in case, but at least ask a pharmacist.