From your history it sees to be urticaria. Many factors such as infections, medicines, food, psychogenic factors, and respiratory allergens may be responsible. Sometime it May be idiopathic as well. If there is angiodema or anaphylaxis is associated or patient starts having any kind of associated respiratory distress, it becomes a serious issue.
Next Steps
detailed history, physical examination with supportive laboratory parameters
Health Tips
1. identifying possible trigger.
2. determine danger signs
3. antihistamines at hand, steroids SOS, depending on severity