The bleeding started a week after my period ended, but my period before was irregular as well. I had brownish blood with a really light flow. Now it has been over a month and I have not gotten my period yet.
How far away was it from your period starting that the bleeding began? SOmetimes, UTIs cause a bit of bleeding, but not like a normal period.
Your urinary tract is separate from your reproductive organs, so shouldn't really affect your cycles, but stress and medication can, so it could be the antibiotics. Maybe an idea to speak to your doctor,