I took Dublin out today to go for a ride and I noticed this lump, bump thing on his stomach. Then I look and notice the left side of his sheath is swollen! The right is a little bit, too..but definitely not as much. I have no idea what could have happened. When I first touched it, he twitched his skin, but afterward he was fine with it. At first it felt like an air pocket, but when you pushed or squeezed it a bit more, you could feel it able to move around - so..probably not air filled. His sheath is swollen and is more sensitive to the touch towards the top where it is closest to the body. I got some pictures of both of them. Any ideas??? A very trustworthy person there said her horse had the same thing and it went away in 2 days. If I don't see any difference or it gets worse in that time - I will definitely call out the vet. However, right now it isn't bothering him, but it's bothering me so I'm just looking for some ideas or hypotheticals. Sorry for the grain-pixel-ness. This is the left..where everything is more evident. Left side again. Bump from behind left - diagonal-ish view. Three-quarter view - left side. Right side. You can see how much more the left side is swollen than the right. Bump from right side. This shows the left and right comparison again. Side view so you get a good idea of how it's different in size. Thanks so much for looking! Any and all help would be greatly appreciated!