Hi Mandypepe my periods started becoming irregular this year and to be honest they haven't really stayed in a reliable pattern. I used to be regular at about the 24day mark as well. In the last six months they have ranged from 21, 25, 28, and 35 ish. I can relate to the slight cramping, but not really like I used to get, similar to what you experience, a stiffness and slight pain in my hips and back, slight dragging feeling in pelvis and usually this has resulted in a period, saying that, I am just spotting with it right now - periods seem to take a bit of time to get going these days.
So, in other words, I think you can safely say your hormones are up and down and these indicators of aches etc reflect this. It could be your levels are dropping before a period/bleed.