If you apply pressure to the area, does she show any indication of pain that way? Can you isolate a specific area that is causing pain maybe by feeling around yourself? Did she start this as soon as you brought her home, or did it start several days later? Is there any edema/swelling anywhere? Possibly something in the fields that is toxic that is causing upset? Is she still drinking, urinating and defacating normally? Is she lethargic at all? Is her heart rate normal?
If you know the people you got her from, can you call them and ask if she ever did this while they had her?
I'd say if you can't come up with an answer, you need to call the vet and let them know what's going on jic you need them. The vet might have other ideas to check and monitor. THen you can set up a schedule for when you should have them come out -- right away, or give it another day or two. But, if anything changes, you need to be on the alert. "Nothing" can change to a serious something in a heartbeat!