3 year old boy. Platelet count 92. Sever nose bleeds, 3 in 15 hours. Small pink dry spots on chest and back, a few on legs. Several bruises, shins (normal for age), and arms. Yesterday he was playing and said "owie" he did not cry, but was pointing to his upper inner thigh. There was a dark purple bruise about 1.5 inches (oblong) and had a hard knot that stuck up as if there was a marble under the skin. Today the bruise is the same but the knot is less raised, hard with defined edges. I'm worried. What could be going on.