Symptoms of endometriosis

So, last month I got my period and there were dark globs in my blood, and my back was killing me. It worried me, but I waited this month to see if it was just a fluke or something else. I started bleeding today, very light, accompanied by the worst cramps of my life, indigestion, dizziness and nausea. Later in the day, I go to the bathroom and there are dark globs again, and now I'm getting some serious pain down there. Could these possibly be clots? I looked up all my symptoms and they all fit into endometriosis. I'm 18, is it possible that I could have it?