Hi, thanks for posting your query to health care magic.
You have mentioned that you are getting itchy crusty spots responsive to steroids on your legs.
Secondly the healed spots are darker in color which is post inflammatory hyper pigmentation.
The itchy crusty spots can be:
Lichen planus- hypertrophic type Psoriasis
You may consult a dermatologist
for exact diagnosis and treatment. A skin biopsy
Mean while you may continue benadryl
for itching and local steroid application.
Avoid scratching as it will aggravate the condition.
For post inflammatory hyper pigmentation you may use de pigmenting creams
once the active disease is treated.
Hope this helps you.