This could be due to a pulled or strained muscle. ( also known as whiplash)
Most likely caused by tension...especially in conjunction with the memory problems.
If you aren't afraid of chiropractors or massage therapists, I would recommend seeing one or both.
If you aren't eating, it sounds to me like stress ( also known as anxiety, depression, etc ).
Stress can do many terrible things to your body.
Acupuncture has helped me, along with massage and chiropractic treatment.
If seeing one of these three does not help, you could try seeing your physician.