Questions-I think one of my BCIs is very sick

[confucius]

I had a thread about this before when it was sort of a minor issue. I had taken said boa to the vet twice, was put on 2 rounds of antibiotics. No changes, things only got worse.
This is an 8 foot BCI. 10 years old. There are bumps all over it's body. The biggest one is about the size of a golf ball. It seems to keep getting more prominent everyday. I started noticing more and more. There are maybe around 8 of them now. A few days ago he spent maybe 2 hours in his water bowl drinking. I thought that was a little odd, but...
Yesterday he was holding his mouth open. No other signs of an RI, and he isn't doing it today. None of my other snakes have an RI. He won't take any food. He hasn't for like 3 months now. Today he was very stiff. I took him out when I noticed some of the smaller bumps getting more prominent, and he usually would try and go slither away. Instead he stayed in the same position the whole time, only moving his head every now and then. He still flicks his tongue. His temps are fine. I have no idea what these bumps are. More just keep coming, and it's really starting to get frustrating. Mainly because I don't know what to do. The vet said they were abscesses, and that the first round of injections would take care of them. I'm really at a loss. I don't want him to suffer but I don't know what's going on. Has anyone else ever dealt with this?