After flushing. It bubbles in basement sink with odor.
How to stop or unclog from inside

Hi singlemom and welcome to The Plumbing Page at AskMeHelpDesk.com. You have a partial blockage downstream from the basement sink. The bubbles are the air being pushed back up the line after the discharge hits the blockage,
The solution would be to snake the line from the sinks vent or if you have a cleanout on a stack you can try it from there. Good luck, Tom