Thanks for the query,
Yes it is possible that she might have developed an allergic reaction
Usually it is itchy but even stinging can be there.
Apply a mild steroid
lotion like desonide
Also give her an antihistamine tablet like levocetrizine.
This will give her 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.