I don't think it would be too good to keep a sick snake in the same enclosure with your other healthy snakes. I would suggest taking out your sick Ball python and putting it in a different enclosure in a different room. You wouldn't want your others to get sick too, vet bills can get pretty darn high.
I would check on your others to see if they are starting to get RI. Raising the temps in the enclosure a few degrees would be helpful too.