hi..thanks for the query.
Redness / red rash as mentioned may be due to :
1) Infections : Like Erysipelas
which is caused by streptococcus pyogenes
.In this, there is an erythematous skin lesion which enlarges rapidly and has a sharply demarcated raised edge. It appears as a red, swollen, warm, hardened and painful rash
.Treatment is by appropriate antibiotics.
2) Herpes Zoster
: In this , before the onset of the typical vesicular rash ,there is an area of erythema accompanied by pain.In certain cases ,there may be no vesicular rash at all.
You should visit a dermatologist
soon and get an appropriate therapy started.
Hope this is helpful.