Two of my lymph nodes on the right side of the neck are hard yet they can still move slightly. I worry that I have lymphoma (I am 15 years of age). I haven't been to any doctors yet but the last time I went to the ER (unrelated incident) they took chest and heart scans and said everything is fine (if that even helps with this discussion). On the left side of my neck, the lymph nodes are soft and very movable and I havev no other symptoms of lymphoma. However, the lymph glands on the right side are unusually hard and stiff (normal size though) since the last time I checked them (they were much softer and mobile). Could anyone explain to me if I should worry or what type of situation I'm in please?

Much thanks