Step-UP Syrup

Hello Doctor ! I need to consult about my mother, Her age is between 50-55. she has a high BP problem since long time, she is on medication of high BP, but sometimes she forgot to take her BP medicine. Yesterday, around 10:30am she felt that her head is spinning, she took her BP medicine & she felt dizziness for about 2 hours & also she vomited. Then after she vomited, she felt relief in her dizziness. then she went to our family doctor, he is a physician. Doctor measured her BP & it was 150/100. He said this is vertigo, and he prescribed medicines. Also, my mother doesn't take care of her diet, her diet is poor so he also described multivitamin capsule for her. She is okay now, she is feeling only a bit of weakness now. So what can be the cause of vertigo? is it because of High BP or is it because of Deficiency of multivitamins?