What could this be?

[Anon4801]

Immediately After sex three days ago I noticed a sort of squiggly like line towards the side of my penis (not normally there) that curved around to the under side of it. it starts on the head and curves around the shaft. It was white like looking at first but since it almost pink like a scar look. It was tender to the touch when I noticed it but not since. It is kinda protruding mostly when erect. It’s not blue like a vein but shaped squiggly like one and curved in like a half moon type shape it isn’t a huge vein but like a small one maybe a total length of a curved pinky . What could it be? STD? At first I thought it was a scratch until I noticed the odd curve and the squiggly vein like shape.

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Agreed with Bucky, docs or sexual health clinic mate, unsure from description