It seems that you are having acute urticaria
There may be some cause.
You are right, it may be some food you ate.
Or it may be some inhalent or some contactant.
You do not worry.
You cosult dermatologist
for firm diagnosis and finding the cause.
You may be advised blood investigations.
He may give you antihistaminics and steroids
in tappering dose.
You will be alright.
I hope you got my answer.
Dr. Ilyas Patel MD