I have a 16 yo son that has been in bed all day with a headache and now he tells me his lower back is hurting too. He hasn't had anything to eat or drink since 2am. I just got home from work and gave him 2 Motrin. Shouls I take him to ER? The low back pain concerns me in combination with headache/fever.

How high is his fever? If you can't get him to the doctor, a clinic or the ER would be in order considering the fever accompanied with the headache.