I am 20 years old and have itching all over my body. It started last night and is literally everywhere... My arms, head, legs, groin, butt, face, neck, ears, etc. I have excema but this isn't related. I haven't changed anything I eat or use. I did spend a couple of days with my in laws and snuggled with their cat a bit that's the only thing that's different. What could be causing itching all over my body? What will help?

Allergy perhaps. Or fleas or mites.
Try soaking in a warm tub with some bath oil, and if you don't have any, some cooking oil. Put the oil in first so that it coats your body as you get in.
If that doesn't help, get some cortisone spray and Benadryl at the drugstore.
If that doesn't help, see your doctor who treats your eczema.