Please call every vet you can drive to in a reasonable distance and find one that is an exotics vet with experience with snakes..
I agree w everyone else. If he was nervous at all about handling the snake I would not trust his diagnosis. It could be he is a nervous whistler, or an RI or stuck shed etc..
But I would still get a different vet for future visits. Not tame? Even my tamest snake will move nervously after a drive in the car to a place he has never seen or smelled before, being held by someone he is not familier with..
As for the retained eyecap. I would never let someone else remove it. I dont care how long it has been there. It will come off on its own with just a little help from you.
Raising the humidity to 75% or more when he goes into blue. Placing a humid hide in his tank stuffed with moist moss during his entire shed process. Rubbing some bacitracin on the eyes once day or so during the shed process.
If you do this it will come off. Just dont saok him during the shed process. This can actually make for a bad shed.
I have delt with retained eyecaps on new arrivals and I have always gotten them to come off on their own with only the assistance I mentioned. Forceably removing them can cause more harm than not.