What Causes Red Rash Over Torso And Thighs Post Fever?

Hi, I have been sick all week. Started off on Monday with fatigue and high temp. Tuesday high temp and severe stomach cramps (a bit like contractions), Wednesday, Thursday and Friday severe vomiting and diorrhoea. Was seen by my GP late yesterday and he gave me a shot in leg to stop the vomiting (worked) and still have diorrhoea. have just had a shower and noticed I am covered in red itchy small lumps - mainly over my torso, thighs and breasts. What is this?? I am taking Domperidone 10mg tabs for cramps and Loperamide HCL 2mg for diarrhoea. I am a nurse myself and don t think it is a reaction to meds??