Have a floor company come in and evaluate it. I have seen a few, that were able to be sanded down and treated and were ok, but, also some that couldnt be salvaged.

Small room. I would replace rather than try to salvage.

As cat said, have a flooring company look at it to see if it can be sanded and stained. If they can sand it, but are not able remove all of the stains, I wouldn't worry about minor spots that may remain if the area is going to be covered by a bed/furniture.