How do you explain?

Today I stopped by Mel's house to drop off my key and some other things. (She is taking care of kitty over Thanksgiving while we are in Omaha.) I sat in the kitchen and talked with Iree (her almost 4 year old) and her. Iree asked "Kim B, why is your face red?" I turned to Mel to see if it was red from a recent scratch or if he was asking about my acne. He was asking about the acne. How do you explain acne to a 4 year old? I was stumped. I can't tell him that its cause my hormones are all jacked. I couldn't even lie and give those things you think when you are younger like "she doesn't keep her skin clean or she eats too much chocolate..." So I just said it was from some medicine that I take and my skin was "itchy" and that makes it red like it is. He asked a few more questions but thanks to mom's help we were able to satisfy his curiosity and we moved to the next topic of discussion. Such is the mind of a 4 year old I guess... taking in all the information in that it can and moving on with the next thought.
On a side note I do think my skin is actually getting a little better. I'll keep taking my meds and keep hoping it will clear as things level off.