Since a few weeks there is a smell of wee in my toilet, and I can't seem to get rid of it. I have cleaned it twice a week with Domestos for the loo, and normal all-purpose cleaning liquid for the surfaces (incl. floor)but it doesn't help. There are no obvious stains, although there is a slight yellow edge where the lino meets the base of the toilet, but that has always been there. Any tips what I should use or where I should clean? Help greatly appreciated!