How do you know the problem is the floor and not the walls. The walls are covered, so you can't see what's there. Don't assume the foundation is not at fault because the tiles are coming up. We don't know where the water is coming from.
You need to do some research and find out where the water is coming from. Do not assume anything!! Making assumptions instead of getting hard facts will not solve the problem.
How many rooms are there? Did anyone consider the heat/AC requirements? Its possible that you've changed the air flow so much that the moisture has can't get out.
Do you have a sump pump? Is it working correctly?
Is the dryer venting properly?
Any other changes in last couple of years, including the outside? How are your gutters? Changes in the landscaping?
How has the climate been where you live? Have you had more rain than the past few years than the previous few years?
Nailing to the floor is very common - don't fault the contractor for that.