I went out to ride this morning and found that my horse has a lump over the fetlock of his right leg. He just got his shots three days ago and got his feet clipped (he isn't shod) a few days before that. He has crap feet and a bit of thrush I've been fighting for a while so the farrier ended up cutting them a little short and his feet were a bit tender for a few days, I don't know if that might have anything to do with it. Anyway, I haven't worked with him/checked him over since he got his shots since I've been working so the lump wouldn't be very old.
Here's some pictures:
He's not favoring it. I lunged him around and he had his normal sass and when I poke and prod it he doesn't act like it bothers him which I would think to be a good sign. Any ideas what it is?