Yes, slowing down like that is very much part of severe depression for some. You might wish to see a psychiatrist as soon as possible and find out which medication is best for you to take to bring your blood chemistry back into alignment.

So much of this is a chemical imbalance more than anything else, but you do need to be evaluated by a specialist to make sure that there isn't something else going on,
as well.

I hope you're going to get better very quickly with the right help.