About 8 weeks ago my hair changed from 'normal' shiny hair to very greasy hair. I have never had greasy hair and now, even straight after washing, a greasy residue is present all over the scalp. I have tried numerous shampoos but with no success. I'm now wondering if an underlying medical problem could be responsible. Has anyone else had this problem or can offer any solution? (I've even tried washing in cider vinegar and washing up liquid). Thanks.