Damp concrete floor

[Aero]

I live ina victorian period home which had a damp proof course in 2006.

A fire place was bricked up prior to me moving in and the paint and plaster bubbled up then flaked off. Any ideas...

and in the same room the floor is concrete and we have had a wicker basket full of toys on top which has gone mouldy - I have put a plastic sheet under a play mat and the plastic sheet even though it is on top of the carpet has water droplets on. The concrete floor has white salts all over and is next to the chimney breast. Any ideas

Cheers