I can feel 2 neck posterior cervical lymph nodes ( less than 6 mm). i have taken an ultrasound scan and the doctor said it was normal(8 months ago). and i can feel 2 groin lymph nodes as well. (less than 8 mm). could it be lymphoma? i m 18 ?

If you had lymphoma, you would also have other symptoms, like night sweats, unintentional weight loss, fevers, feeling sick, etc. If the lymph nodes you are feeling are not increasing in size, they are likely benign. Lymph nodes get bigger with infection but then they decrease when the infection resolves. See your doctor to examine you if they get bigger or you develop other symptoms! Good luck!!

In addition to Dr Ferranti's answer, if you return to your doctor, they may recommend blood work to confirm that these are likely benign. If that has already been done, please follow up with your doctor if you are noticing more or the ones you have are enlarging.