Poorly and late period?

[boymumtoone]

Has anybody ever been poorly at the start of their cycle and then their period was late?
At the beginning of my cycle I was really poorly with a chest infection and had to take antibiotics. I use the Flo app to track everything and 4/5 days after my predicted ovulation (around cycle day 20/21) I felt ovulation pain that I usually get, I took a OPK and that had very dark lines (not peak). I assume from that test I ovulated on days 20/21 when I usually ovulate around cycle days 14/15.
Is it possible I just ovulated later and my period hasn't arrived yet due to that? I'm currently 4 days late and not actively trying to concieve. I Haven't tested yet as I am hoping it arrives soon but wondering if this has happened to anybody else?

I am not ill all that often but my period has always arrived late when i have been ill. My period was 12 days late after a really bad cold a few years ago. My cycle did get back to normal the following month.