swollen lymph nodes and fatigue?

Im a 15 year old female, I have been feeling really tired lately. Im very athletic and I've been getting out of breath going up the stairs. My appetite has go way down also, so i have been loosing weight, like 1-2 pounds a week. Ive noticed that I can feel a lymph node in my neck on the left side, it feel about 1-2cm long and 1cm across, I don't know if thats normal? It has been there for over a month, and I haven't been sick. I have type 1 diabetes (autoimmune disease) so would that increase my risk for something like lymphoma? I don't want to go to the doctor if there isn't anything wrong because my dad hate "babies" and like me to be tough and not complain. Has anyone else had these symptoms, should I go see a doctor? Thanks