We're dealing with one as well with a 5 month old steer. Away from the herd & limping a month ago, temp was normal, no obvious signs of swelling, foot rot, trauma, leg felt fine, etc. Wait & see. Was back with the herd a few days later, kept an eye on him, seemed okay but still lagging a bit, figured he must have tweaked or sprained something. Keeping up with the herd the past couple weeks. All of the sudden he was away from the herd again this morning and his right shoulder is definitely swollen. Got him/mama to the barn & calling the vet 1st thing in the morning.
Tom, I hope yours turns out well and I agree it's probably a sprain, bruise, maybe even got stepped on by her mama.