Thanks for the query,
After surgery plasters are put on stitches.
You might have developed an allergic reaction
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.