odd hole developing in cement floor
Hi--I had noticed over the past, maybe year or so, a small spot on the cement floor of my 70-year old basement. It always looked like a wet spot--about the size of a nickel--and I assumed that it was a stain, it didn't change when I swept the floor, and never paid much attention. If it hadn't been close to the litter box I never would have noticed it.
Today I noticed that it was larger,now about the size of a quarter, and looked like there was something there--I scraped it and the cement was soft and crumbling. seemed damp ( hard to say, maybe it was just cold) and easily gouged out! so now I have a hole in the cement floor, or would have if I kept digging!
What could be going on here? This spot is about 4 feet away from the floor drain, and probably also 4 feet away from the exterior wall. I have had the interior perimeter drains redone many years ago and a sump pump which is working. The basement has been dry since that work was done.
What sort of contractor do I need for this?