So the three days ago Chinga got a scratch where his girth sits, its only tiny and the scratch it's self I just sprayed and seemed to be heeling. I made sure it was clean and sprayed it daily (like the instructions said). Yeserday I rode him bareback and made sure I kept my leg off the sore so it didn't rub or he got hurt. Yet today I went out and about 3cms around the sore it had swelled up, not a massive swelling but you could still see that it had swelled up. I washed it out, although it didn't really need it (but it had a little gunk in it). So I am having another look at it, but I was wondering, what could the swelling be caused by?