Two possibilities are there. It can be pityriasis rosea or hives. Pityriasis rosea is a common human skin disease which presents as numerous patches of pink or red oval rash. The rash may be accompanied by low-grade headache, fever, nausea and fatigue and sometimes by itching.
No treatment is usually required. In most patients, the condition lasts only a matter of weeks or months(upto six months)
If the rash persists then it will be best to get it evaluated from a dermatologist. Other possibilities have to be ruled out then.
I hope it helps. Take care and please do keep me posted on how you are doing or if you have any additional doubts. Kind regards.