what is this red spot on my penis head?

I came home from swimming in the ocean and after getting out of the shower, I noticed this red spot/raised bump on the head of my penis. I don't recall it being their earlier today and so not sure if this is just being in the ocean water, or something i need to see a doctor about. any idea what this is?

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Could be Sea lice. If its still there after a few days go and see a GP