Have you had him checked for anemia? Are you giving him any B12 and B Complex?
I looked at the labs tab and didn't see CBC. I know anemia can cause lethargy. I wondered about BP being too low but hard to tell because of normal vet stress. Talk to the vet when you take him in. I think you said last BP was 140? That is a good number. I don't know how much the stress can cause it to go up and by how much.Last time he had blood work,3 months ago, he was OK. Yes he gets Methyl B-12 & B complex. The change started shortly after I started him on the BP meds.My vet just got a new Doppler to test his Blood pressure.
I'll bring him in next week. Maybe his BP is Too low?