A whole finger evenly swollen, resting bent, tender along the palm side and agony to straighten: those are Kanavel’s four signs of a flexor tendon sheath infection. Go to the ER now, then expect 6 to 12 weeks of hand therapy to keep the tendon gliding.
Red and swollen beside the nail is a paronychia, which often settles with warm soaks in a few days. A tense, throbbing fingertip pad is a felon, which usually needs draining the same day before it reaches bone.
Yes. Any bite that breaks the skin of the hand needs the ER or urgent care today, especially a cat puncture or a split over a knuckle from a tooth. Those two seal bacteria into joints and tendons, and can turn into an infected joint overnight.