We were at a schooling show and Jackson just wasn't acting right. All his lines were crooked and eventually he did move off of my leg, but he was sucking back a lot through corners and turns and just didn't have any 'go'. So we untacked after our flat class and I noticed two things: there was a small line of blood under the pad of his breastplate, which is weird because it's sheepskin lined and nothing was poking or stuck in the sheepskin. And then on his girth area there was a lump (I've attached a picture). It was hot, but so was the rest of him, and now t doesn't seem abnormally warm, it's firm but squishy (if that makes sense?) and pretty big. Someone said it looks like a cyst, my coach told me to hot compress it (did that) but I honestly have no idea what it is. My instincts are to say bug bite, but it wasn't there when I tacked, was right under his girth and I don't think anything could get in there. It's on his left side, which is the side he was bulging on / fussing about moving off my leg but when I press on it it doesn't appear to bother him (granted there's a difference between the pressure of a hand and the pressure of a girth). Any ideas? Does it look like a bite / sting mark to you? He did have one little blow up early on in the day, but I don't think it was big enough to indicate a sting, he just threw his head in the air as I was leaning forward to fix his braids and backed up a few steps.