Thanks for posting your query to HCM.
There are three possibilities of your problem:
cruris/ corporis: The beginning of Fungal infection
of the skin can manifesting as small reddish dots which is due to heat and humidity. By application of powder the sweating part is reduced and so bit improvement.
2. Vasculitis: Mild form of inflammation of vessels leading to slight rash
healing with hyperpigmenation.
3. Purpura: Caused by extravasation of blood leading to reddish spots which turns into blackish in few days of period.
You have not mentioned your age and related status of any other problem and your occupation to correlate the things with above diagnosis precisely. Even then as now these are fading so nothing to be worried, but if are increasing or new lesions are appearing anywhere else then should consult a dermatologist
With best wishes,
Dr Sanjay K Kanodia
MD (Dermatology & STD/Venereology)