Thanks for the query,
You have developed an allergic reaction
Your description of itchy bumps matches with that.
As it is just on one ear probably it is a contact dermatitis
You might have come in contact with a particular thing.
Apply a mild steroid lotion like desonide
Also take an antihistamine tablet.
This will give you some relief.
Please meet a dermatologist
for exact diagnosis.
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.