I've never had appendicitis myself, but my 10 year old son had it this past December. It came on fast. He was fine one day and then the next he was throwing up every hour with horrible pains in his side. He could barely walk or stand up, too.
I would think if what you are experiencing is appendicitis, you would be MUCH sicker.
It may be just something muscular or just thinking about it and focusing on it is bringing on the discomfort.
Hope you feel better.