Simplify your life. Provide the most structured, most predictable, most routine environment you can come up with. Do NOT give him a string of choices. Most of the time NO choice, or yes/no choice, but with due consideration for where he is at. If he hates veggies, you don't make eating veggies a no-choice option (trust me, it doesn't work). But find a healthy breakfast he will eat and enjoy, and he can have that every single doggone morning. To make life easier, do the same for the rest of you (not the same breakfast as he has, necessarily, but the same thing every day)
Bedtime, and bedtime routines, and getting up in the morning, and meal times... predictable. If there are certain treats that happen weekly such as a special meal, make it the same meal on the same day, either every week or every month. Reduce the number of toys. Restrict or remove electronics (for everyone, if this is going to be done, or it doesn't work). Seriously reduce the number of "outings". It sounds brutal, but it's kind of like an elimination diet. Take everything out, then add things back one at a time... it helps in figuring out where the real problems are.
If he's anywhere close to on the spectrum, then he probably has sensory processing issues, which you won't see or understand but which generate HUGE overload, and often trigger problems.
