Mysterious lesion on cheek!

I am a 20 year old female visiting a foreign country and after spending a day at the beach i have noticed a strange, open wound that doesnt seem to be healing. it has been two days so far. The doctor i met with earlier today prescribed an antibiotic cream but didnt have much insight on to what it could be. other symptoms include itching and stinging! any suggestions as to what this could be would be highly appreciated.

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Have a blood test for flesh eating bacteria , it’s very rare but it’s in some seafood and can be contracted at the beach