I Have Had A Rash From My Knee Down It

I have had a rash from my knee down it first started with red welts and burning have apply hydrocortisone and Benadryl even a medrol dose pack dr. Has changed mess to fluticasone cream and another round of prednisone but now the rash is red and deep red blotches are from look like bruises going on 3 weeks it's so accompanied with itching