Could a neck strain or injury cause internal bleeding? in the neck or brain?

Since the severity of a neck injury is so variable, only a generic answer can be provided. Trauma can promote an arterial dissection in the carotid or vertebral arteries and local bleeding at the site can compromise blood flow to the brain resulting in thrombosis or embolism, and the area of stroke infarction can locally bleed. None of this is salient to the typical cervical strain.