I Am 20 Years Old, 5'6 And Overweight, I Was

I am 20 years old, 5'6 and overweight, I was diagnosed with secondary amenorrhea at 15 and without oral contraceptives have not menstruated in that time, it has been over a year since I've been off oral contraceptives. Recently I have been cramping in my lower abdomen/upper pelvis and there is light spotting today, am I starting to menstruate or is it more serious?