Sudden on-and-off pain in a lower premolar is most often linked to early tooth decay, sensitivity from worn enamel, or a small crack in the tooth that reacts when you chew or drink something hot or cold. Sometimes gum irritation or food getting trapped between teeth can also trigger this kind of intermittent pain. In some cases, the nerve inside the tooth may be getting inflamed, which can start as occasional pain and slowly become more frequent over time. Keeping the area clean is very important, so gentle brushing twice daily and flossing can help remove food stuck between teeth. Avoid very cold, hot, or sugary foods for now because they can trigger sensitivity. Using a desensitising toothpaste may reduce discomfort over time, but it takes regular use for a few weeks to show effect. If you notice the pain getting more frequent, lasting longer, or becoming stronger, it is important not to ignore it, because early dental decay or nerve involvement may progress and require treatment like filling or root canal. A dental check-up and X-ray can identify the exact cause and help prevent worsening.