Yes, you should contact a real estate lawyer.
I am concerned, however, that your statements seems to be two-fold and not necessarily related to one another. Also, it sounds like your issues might not be against the seller, but the property inspectors.
The first statement you made is that there were foundation issues that were not disclosed. First, the owner would have to know about the issues in order for them to be disclosed. Second, was there a property inspection ordered? Did the inspectors miss it? Your lawsuit might be against the inspectors and not the owner if they knew nothing about it. Sometimes a property is handed down to someone and they know nothing about the property. That is why you have inspections.
The second statement that you made was regarding a flood, which totally has nothing to do with foundation issues. It is standard that flood areas are disclosed as part of the disclosure packet and have very little to do with the seller. Was this a flood area and did you not know this was a flood area? Or, was this flood not normal for the area and just an act of nature.