Straightening can be a reason. There are many reasons for hair fall or thinning of hair on scalp. So first and foremost we have to find the cause with the help of detailed history and examination. Some of the common causes are nutritional deficiency, hormonal causes like androgenic alopecia or patterned baldness, hypothyroidism, telogen effluvium etc. Unless we find and treat the cause there is no point in giving non specific treatment. Oils or shampoos do not have any effect on hair growth as they are not absorbed in the skin. Moreover, you should never self treat with anything. Please call me and visit my clinic or send photographs using online consult option for proper diagnosis and detailed prescription.