Well how late are you?? if you are more than a week latr take a test. Sometimes you can miss your period due to stress and or exercise
Did you take any antibiotics or medicine in the last month or two? I have a 14 year old daughter that was the result of when I was on birth control, I had taken an antibiotic not knowing that they cancel out your birth control. I was told by my doctor that there are certain medications that will do that. That's why I am asking about the medications that you could have been taking in the last month or so. I felt period like cramping in the beginning, but of course never got a period and after doing a test and it coming up positive thats when I went to the doctor and he said I was pregnant. He actually laughed at me when I asked him how! I was meaning cause of being on birth control pills, and he made me laugh about it cause he at first thought I was asking how do you get pregnant (the bird and bees talk)... but I was scared for nine months cause I knew I was on antibiotics in the beginning with her and on pain meds and was scared something was going to be wrong with her. I am happy to say she is a normal teen... take a pregnancy test first, whether it comes up negative or positive I would recommend a doctor appointment right away. Cysts on your ovaries can cause cramp like pains in your sides...Good luck, and please let me know what you find out!!!