Lymph nodes in neck and groin. Studies?

I am a male teenager 16 with 2-3 palpable lymph nodes in my neck they are not hard and moveable and seem to be in a chain but not attached.I also have nodes on either side of groin which are flat.All the nodes are less or equal to 1 cm.I have good health and growth but i am thin.I do not have any other symptoms of lymphoma and my physician felt my neck and told they are ok and not to worry about them.I don't have armpit nodes.I had mesentric lymphedenopathy but due to stomach issuses(which are improving).I had a infection in past September.My CBC HEMOGRAM ABDOMEN ULTRASOUND were all clear and ok.So do i have to concerened over lymphoma as health axiety is ruining my studies???I have seen two physicians who said i am fine.