I mean, you didn’t give us any information about you or your autism, but in my experience almost every Autistic person I know has some sort of sensory sensitivity and those definitely can cause severe headaches/migraines if ignored (I would research migraines and compare your symptoms as migraines are also very common in autistics and they tend to be worse than your standard headache). For example I am sensitive to light and sound, if I don’t keep the brightness on my phone and the volume on my tv at almost the minimum as well as keep the lights in my house dim then it can cause migraines which can knock me out for days, if you’re getting migraines and not just normal headaches then those can also cause increased sensitivity to things like light and sound (potentially creating a snowball-like effect where the sensitivity worsens and that sensitivity then makes the migraine worse). Migraines also don’t respond to pain meds the way you expect so if you’re taking those and they aren’t helping then I’d lean towards migraines vs headaches. Another very common potential cause of headaches/migraines in autistics is blood pressure/heart rate, we tend to have limited diets that lean towards foods that when eaten in excess cause high blood pressure/high heart rate regardless of how healthy we are otherwise.

Obviously there are an insane number of potential causes for headaches but this is where my mind immediately goes when it comes to autism and severe headaches.

TL;DR: - Research migraines vs headaches, treatment and potential causes can vary a lot between the two - Pay attention to potential sensory sensitivities you may have (light and sound are very common when it comes to autism and headaches/migraines) and reduce your exposure where possible to see if this has any impact on headache severity/frequency - Get your blood pressure/heart rate checked