HelloOne of my fingers has gotten very red and sore
I'm Dr. Branch, thanks for using 'Ask A Doctor' service.
What you are describing sounds like a condition called paronychia, which is an infection on the finger around the fingernail. This usually involves only one finger and presents as a rapid onset of redness and swelling around the fingernail. Usually, there was some minor trauma to the finger a few days previously, but sometimes patients cannot remember.
Paronychia also needs to be distinguished from a felon, since felon is a more dangerous infection that can spread to the bone. Also, paronychia typically has an abscess. For these reasons, it is important that you go to be evaluated by a doctor urgently so that they can assess the infection and probably drain it. You may also need to be started on antibiotics.
I would recommend that you go soon as this is unlikely to resolve on its own.
I hope that helps...
Please let me know if you have any other questions and I would be glad to discuss it with you further.