They’re very common around the mind of autism, especially being triggered by minor things (noise, taste, or change of routine). An emotional breakdown that involves screaming and sometimes hitting. It’s not easy calming them down, especially when they’re still a kid.
In this case, Tim has a phobia for balloons, the loud pop is very unsettling especially against the ear. (I hate it a lot too :|) He’s just really scared, unfortunately others don’t understand just as much as his brothers and mom.
Anything that may calm an autistic person could be a certain texture they like, an interest they love to distract them from their meltdown. Tim loves anything nostalgic and fluffy, like Mr. Bunnington!