Yes the pain on the side is a classic sigh of pancreatitis, so he probably had at least one attack before this one. I also wanted to mention that you said in an earlier post that Jackson always ate grass, but before this attack he was eating a massive amount. I know that animals eat grass when they have an upset stomach, but I don’t think this is “normal”, and I think it should be seen as a sign of distress. Some think it also may mean the dog is not getting enough fiber in the diet.
I’m a little confused about all the comments about no swimming in chlorinated water. A home pool doesn’t have to be chlorinated like a public pool, and even our drinking water here in AZ has chlorine in it. Granted, I don’t know anything about this disease, but I hate to think of Jackson never swimming again.
Is everyone absolutely sure about the chlorinated water and avoidance of ingesting it? I’d ask the vet about this to be sure.