Sorry it took a while to get back to the computer. I managed to get mild food poisoning friday night in addition to all of this.
The vet's office was able to get me in at 10am- which was really nice of them on such short notice. At first the vet thought it was a fatty lump, then she stuck a syringe in to remove some of the contents, and a light red liquid came out... she asked if it had been possible that he had been kicked, because this was basically the dog's body's way of protecting itself after some sort of blow.
Obviously it was NOT from being kicked. I told her that he spends time in the yard with his pal dixon while I"m at work, and something might have happened while I was away, but typically people don't get too close to the yard (to which she replied jokingly "I can't imagine why?"). I also mentioned that he'd fallen off the bed a few days prior and landed on that side. He tried jumping up, but there wasn't quite enough room and he slipped off. She said an impact (I have hardwood floors) like that could have caused it.
The only other possibility was a hernia... she took some xrays and said that she was 85-90% positive it wasn't a hernia because of the placement (over one of the ribs), and because she couldn't feel any kind of 'hole' in the body wall. Told me I had three options: 1) send him for an ultrasound on monday, 2) inject some dye into the liquid filled area and take another xray to see if it leaked into the intestines, or 3) I could go home and keep an eye on him.
I hope I made the right decision, but I decided that I would take him home and keep an eye on him. She basically said that if he developed any sensitivity in the area, lack of appetite, vomiting, fever, or lack of energy to bring him in asap. So far he is going full steam ahead and is chowing down like normal... She sounded pretty sure it was not a hernia, but just couldn't tell for certain from the xrays. We have a follow up visit in 2 wks for her to look at the area again and make sure things are healing.
Oh- and I'm supposed to be keeping an ice pack on it 3 times a day to keep any swelling down. I've been trying but keeping an ice pack on the energizer bunny is quite a challenge. I'm about to try ace bandaging those frozen peas to his side and letting him loose, lol.
One other thing that was odd to her was that his heart rate was way down at like 60 bpm. Said that was more common of a horse, not a dog (which she said is usually at 100 bpm) but that it may just be normal for him. Told me it was something we should take a look at when this is cleared up...
I really hope this is all gonna be ok. Meanwhile we're keeping an extra close eye on him and he's spending a little more time in his crate. I still may get the dye or ultrasound done for peace of mind, but the vet was pretty sure he'd be fine, and xrays/ultrasounds aren't cheap. That makes me sound like such a mizer
Anyway- sorry so long but that's the full report. Thanks again to everybody who lent support and answers!