Is it possible for me to use ciloxan (ciprofloxacin) on a 3 year old child for earache?

Nope: Don't do it. Have the earache checked out by a doctor to determine the cause. Most earaches in 3 yr olds involve the middle ear, so anything one put in the outer ear canal wouldn't help anyway. Even if the problem is in the outer ear, don't use eye medications in the ear. No shortcut here. Get the proper medicine and use it according to doctor's instructions. Hope the little one feels better soon.