I am 26 years old female. Since the past three months I am having delayed periods. Generally I get my periods every 28thor 29th day of the regular cycle. But last month my period was delayed by 11 days. And this month my date was on 21st march and I still have not started with my periods. Also I am taking homeopathic medication for blackening/ darkening of my upper back area. Taking medication since december. Not taking any ocp's or any birth control pills also. My last sexual intercourse was almost 2 months back. I don't know why is there a sudden delay in my periods. Is it of some serious concern?