Grey hair, apthous ulcer constipation.

I have recurring apthous ulcer problem and constipation due to  stress and ib.s and adhd a d lack of proper sleep problem . I have to take any multivitamin three times a day like nurobion forte with vitamin c since last one one day after recovering of bells palsy  which was relief by nurobion forte TABLET. I have shown so many doctor  like gastro and psychiatrist and done many test only folic acid deficiency and I have taken becosules,becosules z but no relief  only nurobion fort with vitamin c three times a day and night lactic fiber and in morning pan 40. But endoscopy result no gas. My hair becoming gray only nicotic and folic acid difference in becosule and nurobion forte Which multivitamin should I take best and for how much time.