I noticed a really small painless swollen lymph node behind my ear&few days ago I noticed a painless small swollen lymph note behind my head. Worry?

Watch and wait. There is no need to worry. You may feel the node every couple of weeks, if the lymph gland doubles in size, becomes painful, ulcerates, or other nodes become enlarged, or you develop fever, or lose weight, you should see a doctor.
For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form.
Practice safe sex, if you have sex.
Not at this time. Lymph nodes can enlarge in response to inflammation or infection. If the nodes enlarge significantly and don't reduce back down in size - would have that assessed.