You might try this to learn more what is happening in your house, we did it alot when complaints came about concrete we sold. low cost and effective.
Somthing like this http://www.pecora.com/pdfs/Tech_Bulleti ... a_Deck.pdf
or this from: http://www.floortest.com/current-test.html
The Rubber Sheet/Plastic Mat Test
This is the most commonly used test. However, its margin of error is very great. For this test, you place a 36" x 36" mat on a clean concrete surface, secure the perimeter with duct tape and leave in place for a minimum of 48 hours. After removing the mat, inspect the concrete's surface for darkening, any signs of moisture droplets, surface drying (whitening) and how well the duct tape stuck to the concrete. Some feel this test can be done overnight or in 24 hours. It has been my experience that nothing starts to happen for 48 hours.
This tells you if water is moving in your concrete, and if so any number of things travel with water, or possibly come out of the coal with water.