Bleeding midway through cycle....

Hi ladies,

I had my second child 5 months ago. I have had bleeding twice through this last cycle. This has happened on day 9 and 13 of my cycle. I never bleed in between periods. Was quite abit. I know it could be a sign of cervical cancer but I know it isn't as just had the all clear. I'm not on any contraception either. Does anybody have any idea what could be causing it? We have only had sex once this month so far....thanks for any replies