Why do I always feel like death the day before I start my period? Does this happen to anyone else?

Like headache upset stomach etc?

Also based on my calender I forgot I was suposed to start today since I did last month? But since ive had my son it hasnt been regular at all... Also today I feel like I'm starving even though I've eaten just about as much as I normally would and still hungry

Guess thats normal some days

Anyways my concerns for today...