When I run the water in the bath room sink (1 level house) The bathtub drain gurgles and it smells like sewer gases coming from the drain:( . Could this be a blockage in the air vent pipe? And if so how do I clear it short of calling a plumber? Thanks for any help you can give.

Acct1

"how do I clear it short of calling a plumber?"
Rent a power snake and send it down the lavatory roof vent. Let the snake out until it reaches the base and then put out 20 feet more. This will clear both the vent and the drain line. Good luck, Tom