I got pregnancy test positive on 11-9-17 my last period on 9-8-17. On 21-9-17 I got only gestational sac no yolk sac. Light spotting from 15-9-17. On 21-9-17 bleeding and spotting 5 to 6 times. On 22-9-17 big maroon dark spot and period like big bleeding in black colour. What does it mean. Why it happens. Either there is any chance of pregnancy chances. I have irritation in vagina also.