Blood clot and stroke!

"I hate commercials" both Jr. and I keep yelling while watching an interesting programs. I particularly hate the medicine commercials! I would rather have the problem than the reactions caused by the medication. But on the other hand, though Jr. hates the commercials, he keeps asking the meanings of the medical terms. 

Yesterday, while Jr. was watching movie while lying on the sofa, I happened to notice a blood clot mart on near his knee. I thought he got it from wall climbing adventure last week. I asked him "How did you get this blood clot?". His immediate question was "So, will I have a stroke?" (He knows blood clots lead to strokes, but what kind??)!! Yeah, thanks to comemercials!!