Hi If headache and vomiting persist, you must take him to the emergency. Though any minor illness like a viral fever too can produce headache and vomiting, in the absence of fever and with persistent head ache and forceful vomiting, you have to visit a doctor to rule out any serious problems. If its not persistent, Paracetamol tablets will do for the headache. Regarding the pain while passing urine, it would be better if you have his urine checked from a lab to rule out Urinary infection. If its suggestive of an infection, you should see your doctor. Its also better to look for any local causes like injury/ redness in the penis. In the mean time make him drink plenty of fluids (Water, Juices, Coconut water, Soups etc). Hope my answer helps. Wish your son good health.