12 day old orphan piglet with diarrhea

I’m in need of advice, I have a 12 day old orphan piglet on milk replacer with diarrhea it has had it for a week I am mixing baby cereal in with it’s milk replacer and have given it pepto in the morning as that was some advice that was given to me, other than the diarrhea it seems healthy, eats great runs around and plays it just doesn’t seem to be going away and I don’t know what else I can give it. It had its iron shot at 4 days old and that was the only injection I also gave it electrolytes for the first 5 days of it just cause I didn’t want it to get dehydrated but not it doesn’t seem to be tired like it was before! Any advice would be helpful!! Thank you