Self harm is usually an outlet for over stimulating. Maybe he needs head phones

In my experience, this sounds like it’s coming from dysregulation caused by the loss of his familiar routine. My daughter gets the same way when we have to stop somewhere unexpectedly that wasn’t part of our planned “adventure”. The best thing I can recommend is aversion. When you see the signs of the oncoming behavior, give him a distraction. Make a plan that involves using his creativity - if you’re driving, look for only blue cars, if at home, color a picture using only three crayons. I wish I could be more helpful because I can understand how frustrating and worrying the behavior itself is. Just know this, you’re doing a great job. If you need anything, I’m on here quite regularly. Big hugs!

The tram at Disneyland is a disaster for us. Waiting area too loud from the excited crowd, the trams themselves are loud. Next time, we will walk, and maybe bring earphones for the noise if we encounter those situations. If you park at the central structure, you can walk to the park. Takes ten mins and a lot of families do it.

overstimulation & change in routine.
Strict routine and those behaviors should subside.