According to the paper work the vet gave me I should go off his past behavior (before he got sick)... which is he had none (until he go sick)
Vet thinks the two (being sick and the PSSM) are unrelated. However she believes being ill triggered the condition to appear, but suggested changing nothing, getting weight put back on him, and riding him like we used to. She believes he will be unsympathetic from this point on... but we will still watch him.
We all agreed to keep him on the purina ultium anyway, because it simply cannot hurt.
Since he recovered from being sick, and got off all the antibiotics, he seems fine. Kicking, bucking, and running just like he used to, we have been lunging him only with no sign of muscle tiring or tying up.
He is currently getting Proviable- EQ Pro Bios and getting the next three months off (Trainer is out of space for the winter and I'm having a baby and any now). So he can fatten back up and enjoy winter turnout time, and the trainer will travel to the new barn weekly to do ground work.