I think it’s normal until you hurt yourself by overthinking and that leads to depression, and it’s pretty dangerous!
To overcome from such situation you need to involve yourself in some activity whenever you think you will go into some deep shit thinking and always make sure you don’t end up in such situation.
I mean if you can manage to think a little and then carry on with your activity then it’s completely fine but not overthinking, it leads to depression.
So start taking care of yourself.