He could be in a transition period. Normally we move or transition to different phases of life without noticing...baby to toddler....toddler to young child...tween to teen ect....ASD kids? It comes with fireworks and sirens. They feel subtle changes in the atmosphere....they can feel rain coming before the barometer changes...

Could very well be sensory overload. My children also suffer from that, esp. my 10 yr old ds and 3 yr old ds. They will cover their ears and just start, for lack of better wording, "freaking out" (i.e., making loud noises to cover up whatever other noise is bothering them, covering their ears. Cry, have a meltdown, etc. This is esp. prevalent in public, when we are out shopping). One thing I do is to hold them close to me (yes, they DO struggle, but I don't give in and let them run off), try to calm them down as best I can. If they are still having a meltdown, I take them outside to our vehicle and let them calm down out there, where no outsiders are staring and making rude comments, gestures or laughing. Hope this helps!

so many reasons could cause this. hormones, weather, illness, allergies, stress....

How old is he? Anxiety can be playing a role also. Anything at all different in his day-to-day routine?