If it looks like a "bulls-eye" it may be a bite from a tick infected with Lyme disease, in which event you will need medical treatment. There are images of such bites on the internet. If in doubt have a physician look at it. If it is a bite from a Lyme tick prompt treatment will eliminate a lifetime of problems.
you may be highly allergic to mosquiotes, i am extremely allergic even though it has not always been this way. when the bug bites me it immediately starts swelling up to about the size of a quarter. its itchy, painful, and embarrasing. i would have an allergy test or talk to a doctor about some really good allergy medicine and cream or spray
Its probably just chigger bite, rub a little vinegar on it it will take the itch out if its still itching paint it with one coat of clear fingernail polish it will seal it and stop the itch
I also would like to know if this could be a sign of a disease or allergy.