Itchy scalp

My LO has been putting medicated oil on her head since she was 1 week old, as My mil says that it is necessary so that wind will not go into her body. Since she was 3 months old, cradle cap started to appear on the area the mediated oil was applied. So in order to combat the cradle cap more oil was applied to removed it. Now she is 4 month old, without the cradle cap already, however her scalp is still a little red and still itchy. Just wondering, if the cradle cap was caused by the oil and if it is necessary to put the mediated oil in the first place? Did any other mummy do it for their LO too? Should I bring her to see a PD?