Swollen lump on wing

[Lorgonis]

I recently got two barred rock roosters approx 4 months old. I placed them in my coop with my other chickens. They were inside their own enclosure so the others could not get to them. I checked in a few times a day and on day two I noticed some swelling on one roo's left wing right where it attaches to his body. I originally thought it might have been a wound that happened while he was being caught when I got them. One attempted escape pretty hard, thought this maybe him. The lump has gotten bigger and is hard as a rock. I allowed both of them to free range with the others today as I thought getting out of "coop poo" might help. I watched both closely as this was first time with the flock. There was pecking but no bullying. More of a you're below me type thing. He ran fine and has no problem flapping his wings and doing short flights like all the others. Just looking for ideas of what it maybe. Thank you and sorry for such a lengthy post. Pics below, best I could do as he's new and not use to me.

 

[sourland]

Difficult to tell from that picture, but it may just be a healing wound. I would observe to make sure he does not get fly strike.