What Causes Red Rash On Arms With Lightheadedness?

Hi i have been feeling sick in the evenings and mornings and today i made sure i ate before i went to work at 1:30pm and as i got into work i started to get the shakes and feel light headed i was a bit hot so i run my wrists under cold water to cool me down then a work colleague said i have a red rash appear all over both arms on my best and my cheeks were pink and my eyes were slightly blood shot i sat down and drank some water yet didnt feel any better they sent me home from work you have any idea what this can be?