Im very young and I have to take birth control pills. For me its because of a hormone imbalance along with swelling of my ovaries (both are potentially dangerous to my hopes of being fertile one day) So I must take it to regulate my functions aswell as my period.
Im wondering if your body is having trouble adjusting and maybe your hormones are imbalanced from the lack of regulation that the pills gave you. Seeing a doctor is probably best. My mothers a nurse practitioner so her information is being caried from what shes told me to you. But seriosuly if your not pregnant, check and be sure your ovaries are not swollen or that you behaviors have changed. (from hormones...)
thats all I can help you with, sorry. I hope someone more helpful posts for you later :)