Darker patch on foot

So I’ve had a slight dark mark on my foot for little over a year, I didn’t think much of it at first as I thought it might just be bruising from tight shoes, however It hasn’t gone down at all and has actually got a bit larger dispite getting new shoes, what do you guys think am I over thinking is it nothing or is it worth a check up? 

https://imgur.com/a/rGw0WGH

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