What's going on with my body?!😭😭😭😭

Okay so I always have a terrible period considering that I was diagnosed with dysmenorrhea and so it's normal for me to have heavy period flows and excruciating pain, however, this time I only felt the cramps & then they went away. Also, my periods last 5-7 days sometimes andthis time I barely bled anything & it lasted ONE day. I don't have sex so I'm not pregnant, what does this mean? This has never happened to me! Also, I have a period each month without fail so it's not like I skip periods either and I'm not on birth control or anything. What could it be?😭Β