Hello. Having pain in the middle of the night and now during days as well seems more like a pulpal pain i.e. pain that comes when the nerve inside the tooth is affected by caries (tooth decay). Even if a cavity is not visible it may be present between two teeth. I would suggest you visit a dental surgeon and get an x ray done to rule out the main cause. If the nerve is affected by tooth decay, you may have to undergo a root canal treatment.