What Causes Redness On The Neck And Chest While On Adderall IR?

Question: I'll preface by saying that I am not prescribed so I know I shouldn't be taking it, but occasionally I take a low dose of adderal IR (20mg maximum in a day) because my class schedule and work load is rather heavy and it helps keep me alert and focused and drastically helps my comprehension and general interest in my studies. I can say it's positive effects greatly outweigh the negatives in my opinion and I plan to try to get prescribed to a low dose and low amount as I find I don't need them while at home and never take more than 4 20mg pills in a week at the absolute maximum.

The side effect I'm most concerned about is an occasional blotchy redness on my neck and chest. It's not raised, nor is it itchy or painful, just kind of annoying. Sometimes it happens and other times it does not (usually if I take only 10mg it doesn't seem to occur nearly as frequently). Other than this, I really don't experience any side effects at all other than the usual sleeplessness and loss of appetite.

Is this a serious concern or is it just that my body isn't used to it (like I said I'm not a regular user)? I understand the drug is a stimulant and therefore can speed up the heart rate a bit and cause the body to feel warm (especially when moving around at work for example). This is the only time this blotchyness occurs.

I would appreciate and insight you could give me. Like I said I understand I shouldn't take it to begin with, but I would like to be prescribed and plan to do so as long as this isn't a real cause for concern.