Chromic Enterotoxemia?

So we have a buck who has always been on the thin side. We are owner number 4...he throws amazing kids. When we got said buck he was put slowly onto pasture for the first time ever and had a bout of the runs. fecal same back clear, did dimethox jik and he was better in a few days. He started to put on some weight...then a month ago he had the runs so bad there was caked poo EVERYWHERE. fecal had some HC eggs, not many...but it was um, a "diluted" sambple. We treated with Quest and he's been on a barage of "goodies"...pepto at first until fir meadow GI soother came, 5 day dimethox, antibiotic, tons of vit. B fortified complex, red cell, copper boluses and we worked him onto a weight boosting diet. It took 2 weeks to get to berries, but we are there and he's doing well on drylot. He scarfs his fees, has kelp & good minerals and his fecal is now clean...but he's still thin and we've always suspected and recently confirmed a bad case of cocci when he was younger. Many Johnes tests have come back clean too. We have now confirmed he has had a bout or two of the runs each year. I'm suspecting chronic entero....but the fecal test is $$$$ around here. I'm wondering about just doing the CD antitoxin anyhow...but I'm assuming the treatment schedule is different for chronic....and then do 2 sets of vaccines down the road. It's be a good time while we have him in a drylot pen...what is the TGS member take on this...do it? I've been told to orally dose him since I don't have epinepherine and not risk the allergic reaction...but man I just don't want to mess up his tender gut again. HE's finally gaining weight...