I found a bite on my leg that has a dark bruise around it like a ring about the size of a quarter.a little tender, no itching. should i see a doctor?

Yes,: Please see a provider, it is too hard to say what that might be without looking at it. Do you have any spider around where you live?

Staph Infection: It is not a bite. It is a staph infection. This skin cellulitis often also has an abscess underneath it. Do not pinch it but go see your doctor urgently for diagnosis and appropriate treatment.

YES: Could be a problem. Check now with your primary care physician to start treatment before you get more symptoms.