I Have A Red Itchy Rash On My Leg For

i have a red itchy rash on my leg for several months.I have tried every anti itch cream but the rash is still there.The ras started three months after taking januvia along with metformin.My dr.switched me to trajenta and the rash came back
.I have been off tradjenta for three months but rash is stiil there.this rash extends from knee to ankle.what kind of Dr. should I see?