welcome to hcm.
friend it might be due to insects bite.
a condition called papular urticaria
where allergic reaction
occur after biting.
but it doesn't happen to everyone.
later on it takes bad shape and colour.
but look treatment depends on present condition of your skin.
some general measures you should take always
1.avoid ares with mosquitoes.
2.wear full sleve in legs.
if they are very itchy you can take cetrizine
a good dermatologist can guide you properly.
i also practice dermatology but it need examination of your lesion to treat properly.
so follow the measures i've told and consult a dermatologist
best of luck.