How to fix a squeaky, uneven floor.

My home was moved to its current location about 25 years ago and then renovated by a very frugal family member who has since passed. It is on concrete piles, though I don't know how deep they go. My floor is VERY uneven and squeaks in several places (in the linen closet I had to use an approx 3/4 shim to keep a 19 deep by 14 wide set of drawers from being tippy, but that is the worst spot I think). I had a contractor replace the insulation in the crawl space last fall and asked him about squeaks and he says there is fire damage causing the squeaks, but there has never been a fire in the house's history that I know of and I see no evidence of fire. It hasn't been a concern until now because it has been a lake cottage. However, I now live here full time and am wondering if it's worth the time and effort to fix this, or should I just suck it up for a few years until I replace the entire house?