SO both of my children have gone through various situations like yours. Son is-16,daughter-12. Kaitlyn was on vyvanse changed to Adderall XR, started at 10mg gradually up to 20(depends on ht/wt). Some children are "power eaters",go through their meds that were suppose to last 10-12 hrs,ends in 5-6hrs. Kates last about 6-7 hrs at the most. My son on vyvanse last 4-5 hrs. Needs a small dose middle of the day from school nurse.
Anxiety can be made worse from lack of sleep. Both children take clonidins and melatonin(this one gradully increased over time with good results)Many of Kates out burst where from not understanding why she couldn't do or get what she wanted at the time. Sleep madde is worse.
Kate when she was younger use to wear noise canceling head phones to help decreases noise in the car,even when we went shopping to help decreases her anxiety. We also use classical music in the house/car depending on her mood. She really responded to the baby eistein tapre-she was 2-9 before we stopped watching them in the car. She also went to see a social worker for a while to help with the yelling/screaming/anger management(especially for when she didn't get what she wanted when she wanted it),now I would think there are more SW that know how to help parents like us and her deal with the anxiousnes they can't tell us or even recognise it.
I taught Kate some basic sign language to tell me if she was hot/cold/hungry/mad/sad/drink. It helped a lot in her younger years. She did stop yelling some. That might be something for your son.

We have used Aderall for our son for a few years now and have stepped up the dosage a couple of times, the third time we did it we found the same thing happened as you are describing so we went back down and he was fine. If he does not take it he looses all concentration and stims a lot so it definitely works. It has shown no side effects and is on the mild side where meds are concerned so we consider it relatively safe.

My son screams and throughs a fit in his car seat everytime the vehicle stops at a light. It is frustrating and distracting. I'm not sure why he does this each time but I wish he would stop.

I've tried the headphones. He hates anything on his head and will take it off. No shower caps, no swim caps, no headphones. I'm surprised he even keeps his hat on during the winter. I will try switching the music in the car to see how he responds to that but his siblings love to hear Cookie monster's C is for cookie song on the way to daycare. Yes, I have to listen to it over and over until I drop them off.