I bought an infill home in the ML King Historic District of Atlanta, built in 1996. I gutted the kitchen and dining room myself, and the last step is to lay my new floor. Herein lies the problem.

I have a very large, uniform hump in the subfloor, approximately dead center in my 2 story house. The hump runs about 10-12 feet parallel to the floor joists in my living and dining. When I lay a 6 foot level across it,the fall over 6 feet is an inch or an inch and a half - a significant hump! In the living room, the previous owner laid a floating engineered wood flooring that is in good shape.

A general contractor mentioned to me that there appear to be wood spacers between my concrete pillars and the floor joists above it... could these spacers be causing the hump (i.e. not allowing this portion of the floor to settle)

How do I resolve this issue? Should I lay the bamboo flooring over the hump as they did in the living room? Should i remove the spacers? Self level the floor? Take out the subfloor, plane the floor joist causing the issue and replace the subfloor?

I'm a single woman so I really need some help here. Any DIY fixes would be greatly appreciated.