Re: Clogged bathroom sink - tried everything!
It's not likely a vent issue since only one fixture is affected and considering the sink drains fine for a while.
The problem could be from a number of causes -- sink drain line running uphill --- wrong type of elbows -- "T" --- etc. Getting to the root of problem without being able to see what's what may require opening things if the drain runs in a wall or the floor -- which may be the case to fix the problem.
Best thing is to get a plumber to actually troubleshoot the problem rather than just snaking out the line.
"" an ounce of perception -- a pound of obscure "