What Could Unusual Cramps And Nausea During Menses Indicate?

Hello, I use Progyluton tablets to manage my irregular period, it's been working effectively for 5 years now, and i always get a regular period with pain, nausea, cramps and moderate bleeding this month at the time of my period i didn't bleed as usual just some spotting, but the pain , nausea and the cramps are there..Is there any reason for that? should I worry about it ?