Does anyone know if it’s usual to have an LH surge just before your period comes?

My period is 4 days late, I’m definitely (sadly) not pregnant, I’ve taken lots of tests over the last week, all negative.

I was quite sick earlier in my cycle & had a course of antibiotics which I assume has delayed ovulation, but is it possible it’s delayed ovulation by 2.5 weeks?

I took an OPK just cos (I thought I had light ewcm), and it looks positive.

Could I be ovulating now? Or is there a surge before your period?

My body doesn’t seem to know what’s happening lately!

Any insights appreciated! 😊