Suggest Treatment For Hair Loss And Nausea

I have had nausea for the past few days. Eating something seems to help. I am recently vegan (3 months), I have been taking a multivitamin every day. I am also on birth control (Lutera). When I first gave up animal products, I was losing hair more than usual, so I increased my vitamin intake. I don't know if the nausea has to do with my diet, but I would like to know some possible causes?