I am concerned about an area of discoloration on my lower back up to my neck, it is a brownish color that is a completely different color than the rest of my skin, it is very patchy looking almost like a rash. It has not always been there but has gotten progressively worse. Does anyone have any ideas on what this might be?

Check melasma and hyperpigmentation.

Below is a link to an article on hyperpigmentation on MedLinePlus, the National Institutes of Health database. FYI, "hyper" means excessive.
http://www.nlm.nih.gov/medlineplus/ency/article/003242.htm

If you're female and on hormones [birth control pill or hormone replacement therapy], pregnant or have recently given birth, melasma is another possibility.