Well, your breeding plan sounds like a good one. But you may end up being in the market for a better/healthier buck.
How long are you keeping him off of milk and on electrolytes, They can get Potassium poisoning.
I would give him some Spectam Scour Halt for pigs. (specta GArd) It is a red liquid.
Or since he is on antibiotics I would give him pepto bismo a couple of times.
he looks very young. 3 or 4 weeks, can't imagine he is 7 weeks. He needs to be put back on milk. they require a high protein intake at that age or their bones wont grow. Not to mention the calcium.
Do you have any access to alfalfa hay? That woudl be good to get him started on.
Lice are very hard on them. It really drains them, literally, and treating the lice should help him a lot.
Look and see if you have Land O lakes powdered milk replacer sold by you, It is Called Does match, Mix a half a batch, which would be 2 cups and start adding that at the rate of 25% tomorrow, then 50% the next day, ect.... But go easy. He sould be eating 3 or 4 bottles a day of 8 to 10 ounces, If he was doing well. STart with 2 or 3 ounces of milk and go up from there. When he stops scouring stop the electrolytes, he will get potassium poisoning and just get weak and die.
Add probiotics to his bottle, if it isn't in the electrolyltes.
Good luck with him.
Personally, I wish the vet had given him C&D antitoxin.
Did he check him for Coccidiosis. on top of all his other issues. Did he think the antibiotic he gave you woudl treat the cocci? I am not familiar with that particular antibiotic.