A.C.
I've suffered from this "red rash" since I was a kid, and the rash occurrence has been narrowed down to strawberries (15 years later). I still get them, but since I eat strawberries very rarely now, I was able to see that they are the cause (cause/effect). The rash is bright red splotches, typically located on the lower body (thigh/butt/legs). This tends to clear up within 1 week, but can last longer (typically if one continues to eat strawberries). I hope this helps, as I wished that I knew when I was a kid what caused this.
To further this, type O blood types are recommended to stay away from Strawberries (probably b/c of the acid). Type O blood types are known to already have a high acidic makeup--needing to stay away from fruits that have a high acidity level (like oranges, etc).