I had a headache for 3 days and sharp pain in my left eye the 3rd day. What could be causing these symptoms?

Migraine. These symptoms come along in migraine, glaucoma, brain tumor, eye nerve inflammation and others. Your should check with your doctor to determine the cause of this pain.
Anything. Headaches can come from fatigue, sleeping too much or too little, eye strain, sleep apnea, snoring, being dehydrated, having chronic sinusitis or allergies, too much caffeine or over the counter headache medication, high blood pressure or something more serious like a tumor. See your doctor and get checked.