Talk to General Physician on Nutritional Supplement Usage

A dermatologist prescribed me some dietary multivitamin supplements. He just mentioned the brand name but did not tell anything about which product of the brand should I use as there are many multivitamin products of the same brand with different %DV of nutrients. I am also not sure whether brand products are Halal certified or not as products contain gelatin(source not mentioned) which they usually take from pork, beef(not slaughtered in the right way) and pig. So I need guidance about the Multivitamin supplements brands and their products, their dosage etc.