Mustang Saga

Tonka had to go back to the vet this afternoon.  He isn't eating, drinking, pooping, or peeing enough.  It's pretty apparent that he's in tremendous pain, but the question is, "Why?"  His heart rate was 3 times higher than it was yesterday after the accident, and he was trembling with pain.  His bowels seem fine as far as they can be palpated.  He got some oil and water tubed into his stomach to help things move along.  The fact that his stomach accepted the fluids readily is a good sign that things aren't completely backed up.  Could it just be muscular pain from his EPSM, and wound pain?  Or is there some deadly internal damage?  If he's not much improved by noon tomorrow we'll draw blood, which will give us some more clues.