Hello,
These small bumps can be due to contact dermatitis or allergic reaction to the socks, shoes etc , heat rash, insect bites or lichen planus if the rash is violaceous in color. I suggest you to get it evaluated from a dermatologist to confirm the diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
i have the same thing ive been using gold bond triple action,extra strength in the green bottle.it seems to really help if i apply regularly through the day.