thank you for your query.
Firstly, you need to provide me the details regarding your last menstrual period, pattern of your menstrual cycles, etc to comment whether the bleeding is ectopic pregnancy
If you are around the implantation bleeding phase, I wonder why you took a pregnancy test.
With history of ovarian cysts ( I assume polycstic ovaries ) then if your cycles are irregular, you need to consult a gynecologist to ascertain whats going on.
Also the burning sensation and diarrhoea
point towards a mild pelvic infection
Considering the possbilities, please consult a doctor at the earliest.