Okay so my husband came home yesterday from work and wanted sex...he rubbed his well u know on my butt and now there is a red welt high up in the crack almost on my back and it's very painful...jw but should i go to the doctor? it hurts to sit down and sometimes it hurts to walk around...was is caused by my husband's semen? Should i wait and see if it goes away in a day or so?
The redness, welt, and speed of onset suggest this could be "erysipelas" - an acute bacterial skin infection that requires antibiotic treatment.
The infection is typically caused by streptococcus bacteria breaching the outer layer of skin via a scratch, or skin weakened by a prior fungal infection - both commonly occurring in the region you describe.
You should see your Doctor sooner, rather than later as the infection can spread rapidly.
