If he's putting weight on it, then it's unlikely anythings broken. Check his feet for cuts/anything sticking in them (including between his toes). If you can't find anything obvious, gently feel down his leg - checking for lumps & bumps, then apply some gentle weight on his shoulder.
He may have twisted something or had a scuffle with one of the others. Do you have anyone near you who can give him a Metecam jab to make him more comfortable? If not, Arnica is good for sprains/bruises - is there any way you can separate him from the others, so he can rest it?
Unless it's anything serious, he should get better in a couple of days.
BUT if he's in a lot of pain - call the vet.