Thank you for your query.
Red dots on the legs following stomach pain can be suggestive of purpura
. However you mention that they have grown and itch which can also be suggestive of urticarial which is an allergic reaction
As the doctors have mentioned that the red dots something to do with blood vessels they would be performing a battery of investigations to come to a diagnosis.
I hope I have answered your query to your satisfaction.
Wishing you an early recovery.
Rajiv K Khandelwal