Development of stutter

Development of stutter I am 15 years old and a few days ago, I developed a stutter. It is mild and mainly stutter letters like I, the, they, what and also a lot of words starting in s (e.g so, sweet). It started suddenly. I had a cold last week I don't think that caused it as I have had colds before and never developed a stutter. What could cause this sudden stutter? **EDIT: It is getting worse**