I Was Stung On The Back Of My Neck Two

I was stung on the back of my neck two days ago by a wasp which left a small painful lump. I applied ice to it which reduced the swelling and pain. However, I have just noticed that the lump has increased to about and inch in size but is not painful. I believe it may be cyst but I'm not sure if it would go away over time or should I go to a doctor to get it removed.