If it is coccidiosis, treatment ASAP as it damages the walls of the intestines and they will have more problems as they grow with just not being good gainers. Corid will work, and Spectinomycin for pig, red liquid will also work. I know of no natural treatment that will help once they are scouring. Cleaning the pens and not letting them root in any wet spots/manure helps until they are back feeling better at the least. Coccidia are present in the ground and anywhere... the biggest problem with pigs is dehydration...
Use a syringe to get it down their throat... and I would use 1/4 cc STRAIGHT out of the bottle... not the dilution they suggest for 5 days in the water... My old vet years ago told me to use it for coccidiosis in calves... 1 cc straight per 100 lbs... for 3-5 days..... figuring the pigs weigh 15-20 lbs? They should look and feel better in 12-24 hours....make sure they are getting as much as they want to drink so they don't dehydrate.... milky feed helps if they will eat it... and only give them as much as they will eat in 10-15 minutes so it doesn't get too spoiled and have flies laying eggs in it.... if they will eat good you can mix it in the milky feed after the 2nd dose...
I know of nothing natural that will work on it once they have it, but things like apple cider vinegar in the water, and some activated charcoal for them to chew on .... will help.
If the lining of the intestines is badly damaged, and they dehydrate, you are fighting an uphill battle so the sooner you treat it the better....
