What Causes Swollen Lymph Nodes And Break Out Of Rashes All Over The Body?

Hi my wife has swollen lymph nodes on the back of her neck witch is causing very bad headaches. She has broken out with a rash all over her body. Red and raised and very itchy. She all of a sudden has a problem with her hip too. If that has any relevance. She has complained about pain in her stomach too for a month or two. I finally talked her into going to the doctor and all she knew is that her body is fighting something pretty hard. Still waiting for the blood work to come back. Quick strep test came back negative. What do you think it could be. And what can I do? To figure out what it is to get her the right help?