I have a lump on my finger that is sore to touch and slightly red. It is on the side of the distal inter-phalangeal joint. What could it be?

Splinter. You have noticed a red tender spot on your finger. Commonly it could be a foreign object like a splinter. Try to recall if you did any unusual activity. It could also be a cellulitis if the skin was recently scratched. Make sure you are up to date on tetanus. Keep the area clean and dry.