Phantomcolt18 was almost right :) !!!
The vet came out early to look at another horse so I asked if he would look at it real quick before he left and he said that it was a mixture of darker pigmented skin/some kind of sap/ and thicker hair!!!
We think she got the sap on her before we got her but I thought that it was really weird!! I am sooooo happy I know what it is now!