Hi, I have the middle unit in a three-unit townhome built in 1983. My upstairs floor is very creaky throughout -- neighbors who have fixed the problem told me it's because the subfloor (I have carpet) was installed with nails instead of screws. Okay, I understand that. But the problem is so loud and other indications, like cracks, indicate that I have a bigger problem then that, a loose or broken support beam. The floor doesn't feel soft, but in places wood trim seems to be disconnecting and other strange things. Can anyone tell me what kind of specialist I need to call in to take a look at this and what might be involved? I need to re-carpet anyway, so I was thinking of having it the old carpet upstair pulled up and living on the subfloor for a while until we can figure out what is going on. Any suggestions about how to proceed will be helpful. I'm not a DYI on this project, I need an expert.