I had a blood stain on my hand and I don't know where I got it from, I checked every part of my body, and I didn't see any wound on my body and I have been using the same hand to touch my eyes and nose without noticing the blood, if the blood is from a hiv person, because I'm staying with my brother who is hiv positive, and the blood must have entered my eyes and nose when I rubbed them, am I at risk