Hello and welcome to HCM.
Thank you for your query.
Birth control and diabetes
can both cause menstrual irregularities. The presence of a brownish discharge can also be associated with the use of birth control.
The main aspect of your query would have been your sexual status, which you have failed to mention. If you are sexually active, then we could consider pregnancy
or even an infection.
But even if you are not, an infection might have to be ruled out, for this you will have to visit a doctor for a physical examination and even provide your urine for examination in a laboratory.
I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications at: http://doctor.healthcaremagic.com/doctors/dr-shoaib-khan/64581 . I would gladly help you.