Period late

My period was supposed to come 4 days ago! Tomorrow I will be 5 days late, and I've seen 0 sign of blood coming out of me. I get a specific cramp when I start my period and I go to the bathroom and the blood has started. I get it sometimes when I don't start my period, but when I do it means I'm gonna start my period very soon or I just started it. I keep getting cramps like that and getting excited that I've gotten my period but I haven't! Ugh! I'm not sad that I haven't gotten my period, I'm just worried because I don't know what's wrong? I haven't had sex, by the way, so I'm not pregnant. Can someone help?