Why for pain

This may only apply to women and sorry for that men but this is just a few questions I have about us women.
I don’t understand how I have different symptoms every month. Does any one else have this problem? Each month comes at the right time yet don’t even know what I’ll have.. 
Back pain, cramps, bloating, yes I know this is vivid and very different from from I’ve ever talked about but I’m very bothered by this. I will have another post up later today discussing what men and women both might (hopefully)  find interesting. And if any one has any comments so I know it’s not just me please enlighten me. Thank you