Gf irregular cycle cause

Hi everyone!

I usually help my gf keep track of her cycle and I’m concerned about this particular cycle. During menstruation she had a severe flu and bled for 9 days which isn’t normal for her. Now her cycles are around 25-28 days but her period is now almost a week late. She’s really stressed and she’s extremely anxious and I just want to help her. Can the flu affect her period that early on? Am I overreacting about the bleeding?