Thanks for the query,
Probably you are suffering from urticaria
It is characterised by red raised itchy rashes on body.
Usually the patches are small,
But sometimes large welt
like lesions can appear
It is a type of allergic reaction
You may require treatment with oral anti histamines
Please meet a dermatologist
for exact treatment.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.