Hi, welcome to the forum, the pain and swelling in the finger can be due to pulp space infection or traumatic arthritis. If there is throbbing type of pain suggests pus formation. This may not be due to allergy.
The plain radiograph will help to rule out pathology. Finger splint may be needed to give an absolute rest to the finger. Pain killers with anti-inflammatory activity will helps to reduce the inflammation and antibiotics to control infection, against prescription. I suggest you to consult physician. Take care and regards.
I had the tip of my right index finger crushed in a door about seven years ago. It required several stitches, the x-ray did not show a repairable brake. But the bone had been crushed. It healed and everything was fine until about a week ago. I have not re-injured it, but it is hot, slightly swollen, sensitive to touch and painful. Feels like the pain is coming from, the bone. Can this be related to the previous crushing injury?