NEED ADVICE: 3 periods within a month?

Erika
Hi ladies, 
Looking for advice! I've had 3 periods within a very short period of time and was wondering if its necessary to see a doctor, or if any of you have experienced something similar! I had a period April  19-23  that was very normal! I then had another period May 2-5, that was a little lighter but still fairly normal. Yesterday I started my period AGAIN, and so far it's been pretty light. 
What are some causes of having this many periods 
Thanks!!