What is this? Does this look serious? Please help

Im 17 and I have this thing on the back of my upper calf, I dont know what this is now, I've asked online and people have said scabies, lupus, staph, and lyme which made my health anxiety spiral! I was outside when it was dark and just assumed I was bit by a mosquito since it itched a little at first no I am not so sure. I just assumed it was a spider or mosquito bite! Please help me.