Effects of Black Mold?

I saw my little brother earlier (he is 3, and will be four in late July if that matters) over by an area of our house which has a mysterious black substance that looks almost like black mold, which I have heard is a very dangerous type of mold. I don't know what it might do. He appeared to have physical contact with it, and may have inhaled it. Please help. Should I take him to the hospital? Is black mold toxic? (The reason I am being so paranoid is because of a dream I had the other night in which a foamy white substance came out of his mouth and he died). Please tell me what to do. Thanks!