Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history I can not tell you what the specific cause of your symptoms is nor make treatment recommendations, however I will try to provide you with some useful information.
One-sided head numbness is an unusual symptom, and I would need more information in order to provide you with more information regarding possbile causes. An episode of head/face numbness preceding or associated with headache may be part of a migraine disorder. If by numbness you mean tingling or pins and needles sensation, one possibility is a pinched nerve in the neck that is causing these symptoms. This is medically termed a radiculopathy, and could be due to arthritis of the spine or a herniated disc. This would best be assessed by an MRI of the spine. If you are experiencing numb symptoms in the face, other possible causes include a problem with the trigeminal nerve, the nerve that supplies sensory innervation to the face. Finally, lesions in the brain due to various causes including but not limited to tumors, multiple sclerosis, strokes, can cause face numbness but would then be associated with other symptoms such as muscle weakness etc. This would be best assessed by an MRI of the brain.
I recommend you discuss your symptoms with your primary doctor/family physician. After he/she examines you, he/she can determine whether or not further testing and whether referral to neurologist is warranted.
Thank you for using the forum I hope you find this information useful good luck.