question about bleeding

sorry if this is tmi! i'm not due til the 5th aug af/bfp. last night after some jiggy with my husband there was some blood when i went to the loo afterwards which was bright red and then got dark brown. there was no 'injuries' and think its too early for ib or af and i'm regular and dont get spotting inbetween af's!

any ideas ladies?

cx