Understanding Irregular Periods: Causes & When to Worry

Question
I am 34 years old and have one 13yr old child. Since the age of 13 my periods have been very regular 25-26 days.  My last period was on July 24th and lasted 4days then again on 6 Aug lasting 4days. When should I expect my next period or could this be a sign of a problem.  

Answer
If your last normal period started on July 24 (25-26 days from the previous period) then the bleeding that you had on August 6 was a normal mid cycle bleed (ovulatory bleeding).
This is due to the drop of estrogen in mid cycle, just before progesterone rises. It is normal in some women. You should have gotten your normal period on August 21. If you don't get your period by August 28, take a pregnancy test. If it is negative, discuss it with your doctor.