i have a friend whose son developed a rash similar to what you are discribing and it is probably from the chemo.
Hi
Welcome to the MedHelp forum!
A localized rash is unlikely to be due to any drug. Itchy localized rash can be due to allergic dermatitis, eczema, contact dermatitis, shingles, psoriasis, fungal infection like or Tinea corporis. It is difficult to comment beyond this at this stage without examining the rash. Please consult a skin specialist.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!