Cramping but no blood

My period is suppose to start in two days, and usually it comes a day early. I was at work yesterday and I was getting really bad cramps so naturally I though I got my period. When to the bathroom wiped and no blood ( not even a hint or red/pink). And I thought it was weird, but just in case I wore a pad. But today still no blood but it feels I am on my period. I am getting a little paranoid I don’t think am prego, but it makes think about STI. Just hoping it will come soon.