Why did my cat wee blood? PLZ HELP!!!?

My cat, Madeline, is 10 years old. Well, this morning, my cat looked like it did a wee. But, instead of wee, it was blood. She loved to be touched, but she keeps running off. She is an indoor cat, but sometimes goes outside. Is it something she ate? Or is it normal? And she is desexed, so she isn't giving birth. Any answer will be much appreciated. Thanks. :)