Paronychia (Nail Infection)
This condition is called Paronychia, which is
usually from a bacterial infection. Normal, healthy skin has thousands of bacteria on it but sometimes this bacteria can enter the skin and start to cause problems, as in your condition. I wouldn't suggest a fungus cream unless you doctor diagnoses you with a fungal infection. Your doctor will most likely put you on an antibiotic and lance the swollen patch on your finger and squeeze the "pus" out to alleviate your pain. Soak the finger in warm water 4 times a day. I've also enclosed a picture.