I Recently Just Ended My Period Cycle After Having It

I recently just ended my period cycle after having it for 3 weeks I havent had it for at least 4 days now and today while at work I held in my urine for half the day, then went to the bathroom and then didn't go for at least 5 hours, when I got home I went to the bathroom and when I urinated it looked as if my period came back..... why is this and is it normal .....also I must say I have been really irregular thru out my whole life on my cycle