Has anyone had a period that skipped a few days in the middle

After not having a period for nearly a year, I started a diet that helped regulate them. For the past few months ive had normal periods that last about a week. This month I had my period for a week and thought that was it. Well 4 days later it came back. Has anyone else had this happen?

Also ive noticed that when my period comes at a different time than glows 'predicted period' my ovulation time doesnt change. My ovulation day didnt change even after the '2nd period' came. I know isnt 100% right but i would think the prediction would change or am I wrong. TIA