You have cellultis.
Minor trauma or erosion or folliculitis
would be there..
You may be hving tender warm minor flate swelling.
Do not go to find out the cause.
It is superficial bacterial spreading infection underneath the skin.HIV
,DM and other immunocompromised conditions should be ruled out.
Take strong antibiotics with anti inflammatory drugs till you feel better.
However, you consult dermatologist
I hope you got my answer.
Dr. Ilyas Patel MD