Not a lot to go on but I have a few guesses:

I suspect that your drain is partially clogged with paint/plaster/drywall mud/grout or similar building materials from the remodeling work that was done.

Forget the drain cleaners that you pour down the drain. Instead, use a plunger and rigorously plunge the drain with the overflow covered with a wet rag.

If that doesn't work, snake the drain with a small plumber's snake.

Drains can clog with nasty stuff that includes hair/soap/and gross gook. Drain cleaners often only melt the stuff together. It takes some good mechanical action to clean it out-- particularly if there is some construction related materials in the drain.

Without using a large 3/8" diameter snake, my best experience has been with a "drian king". The drain king attaches to one's garden hose. I'ts a bladder that inflates to build up pressure then lets out a little pressurized blast. The unit does this so frequently that it sounds as though it's buzzing. There is a Professional Plumbers version with a lined canvas bladder for about five times as much money.

ooh, that Drain King looks like a neat idea.

Here are some links:
http://www.kk.org/cooltools/archives/000190.php

http://www.gtwaterproducts.com/drain.html
(adapters for attaching the hose to the faucet)

Our old home tub would clog periodically and we solved the problem with a $2 drain strainer from Lowes (similar to one below). It needs dumping about twice a week, we're not going bald but you'd be surprised how much hair and stuff accumulate in a snap. Any obstruction in your outgoing pipe may be collecting it for you.

{{!gwi}}