Hi there, I have a few concerns about my period. I am sexualy active with one partner the only partner I have been with, been with him for three years. I can not take birth control because every type they have put me on I ve had an allergic reaction. This month I did get my period on time (every 28 days I get it ) always on time. But this time instead of a red even flow, it has been black and very thin watery like and light. I d like to add that I had been on antibiotics a week before I started my period if that would make a difference in it, I had an infection in my chest. I would love to get some answers to see if its serious enough to contact my doctor. Thank you.