Missed period and spotting?

Could be systitus a urinary tract infection due to back passage bacteria getting in the front or due to the displacing of the urethra during sex. Tends to cause the feeling of constant urination and blood with urine. Be sure that you know where the blood is coming from, so either in the urinary tract or the vagina... This could help you have a better understanding of what's going on. Do test though. If you are stressed or have had a weight gain or loss your period may be delayed or even totally missed. Good luck xx