Aiyo, 4 year old boys memang macam energizer bunny, tapi kalau dia really tak boleh duduk 5 minit pun and everything goes to his mouth still, I think worth bringing it up with your paediatrician, they can refer you to a child development specialist or occupational therapist if needed, just to rule out anything and get proper assessment. My nephew was macam tu juga and turned out fine, tapi better check early kan than wonder later, the earlier you catch anything, the better for support. In the meantime, try short focused activities (like 10-15 minutes), lots of outdoor running, and keep distractions away (phone, toys all over), tapi don't stress yourself, you're doing the right thing by noticing and asking.
Nadia Abdul