I found a mole today (Friday) on the back of my thigh, I'm not moley at all so spotted it. It was raised and felt dry n wasn't a circle, it was uneven. 100% it wasn't there on Wednesday as I took a picture on my phone (progress gym pic) and there's no mole! I have pictures on my phone from today of the mole. Called doctors and have appointment on Monday. Went to gym and for a shower. And now I went to check it before bed and it's gone. No trace. No mark that I can see where it was.... how?! I sent pics to the doc (telephone consult obvs cos COVID) and they wanted to see it in person. It was super clear pic! 
 

I just need to know 1) can they just appear and fall off in the space of literally 2 days? And 2) should I be worried/still go to docs? I've nothing to show now though...

Confused.