White cm, minor cramps, period 2 days late. Why?

What could it be? I'm not on birth control, I have had sex with condoms, my period has been regular for many years, I'm not overweight, I dont have any conditions.

My breasts are a bit tender...this has never happened before to me. Has this happened to you? What was it? What could it be? What's the soonest I can test and get actual results?