Baby afraid when mouthing

So anyone else’s LO put something in their mouth and they are fine then all of a sudden aren’t? My son will do this with toys and sometimes even his own hand. He will be examining it and put it in his mouth then he’s loosing it. I have to take it out for him.

I should add he gets very hyper and almost over stimulated with flashing toys and he starts to bulge his eyes and breath heavy until I shut them off. He is afraid to sit in his bumbo and high chair. He will be content for a moment then realize he’s in it and freak. I’m a first time mom and my friends don’t have these issues so just wanted to see if anyone else’s LO did this. He is 4 months next week.