2000 chevy Blazer overheating and boiling over

What is your question?

2000 chevy Blazer overheating and boiling over Overheating, coolant boiling out, no heat , knocking noise a time or two when it's really hot , major smoke from under the hood and bad smell of burning coolant when shut off after

How long has your 2000 Chevrolet Blazer had this problem?

Almost a week