Nailbed melanoma?

I've had a tiny brownish dot on my pinky toe for at least the last three years. My podiatrist dismissed it but I have my concerns. About five years ago, I used a UV light on my toenails maybe about 10 times.

The think is that I filed down on across the top of the pinky toenail as it was quite thick. Then, quite stupidly, I left the UV light on for too long (5 mins?). I'm thinking I may have caused DNA damage to the cells under the nail bed.

I would think otherwise except the dot hasn't moved/grown out at all in the last several years. Also, I noticed a teeny, tiny black dot (circled in blue on the photo). Never saw it until I took and enlarged a photo the other day... Ideas of what it might be otherwise? TIA.