Confused please someone give advice

So I never have cycles shorter than 27 days... normally anywhere between 27-33day cycles are normal for me. Yesterday (6dpo/CD 22) I had some really dark deep colour red bleeding after I had mild cramps for about a minute... it was only when I wiped them twice more that day but it faded to pink discharge. Today I had nothing for 5hrs then when I went to the toilet at lunch there was blood in the toilet like normal menstrual flow. This continued on a pad for an hour... now I'm back to nothing again... I have no other signs of my period that I normally get (spots, cramps mood swings sore boobs and severe tachycardia) and my bbt is still high when I normally dip the day before AF! Anyone have any insight? This is totally out of character for me since I started having periods 12yrs ago