What is this??

Regena

According to glow, I ovulated on the 12th but my ovulation test was positive on the 14/16. Yesterday evening on the 21st, I seen very light pink blood on my tissue. My period isn't due until this Saturday (26th) but I've been having very light lower abdominal cramping. I haven't seen any other signs of bleeding since this light spotting yesterday. My periods are always irregular. Is this the start to my period or could it be implantation bleeding?