Best thing to do is go see a doctor as they know your history, and can provide proper treatment etc...

From the symptoms seems like it was a wasp. You can go to hospital and they will give you tablets and cream, but usually it lasts for a week no matter what you do. However it is important to make sure that the sting came out!! You can try and put vinegar on it and it should then take it about a minute to come out. If I were you id go to hospital just to in case.