My Daughter Has Had Swollen Glands In Her Neck For

My daughter has had swollen glands in her neck for about 4 months. She was tested for strep and mono about two months ago, and took a round of Amoxicillin for sore throat. The sore throat went away, and the glands shrunk some, but now are swelling and painful again. She says it's giving her pain in her neck, which is now causing a headache. Could the swollen glands be something else besides a cold?