What could be the cause of sudden sharp pain under my fingernail?

When you feel a sudden, sharp pain under your fingernail, it is most commonly due to a little injury you might not even notice. This can happen if you accidentally bump or press your nail, causing a small collection of blood to form under it, which we call a subungual hematoma. The buildup of blood creates pressure on the nail bed, resulting in a sharp, intense pain. Sometimes, the pain might also be due to a small infection or irritation in the nail fold even without an obvious cut or bruise. To help ease this kind of pain, you can try applying a cold compress to the affected finger to reduce pain and swelling. It is important to keep the area clean and avoid further pressure on the nail. If the pain continues, becomes worse, or if you see signs of infection like redness or pus, you can use Ubie's free AI-powered symptom checker to better understand your symptoms and determine whether you need to consult a healthcare provider for proper treatment.