High Diziness. Reason? is it serious?

My father is 59 years old. Today while making his tea he felt dizziness. He started saying earthquake came(but it didn't)and he started crawling outside. He stand and suddenly he sat due to dizziness. He said he never felt this kind of high dizziness before. We checked his blood pressure which was 141/86 . He didn't feel any pain in his chest and head. From last two- three days his centre and lower back is paining. He doesn't feel pain every time but few times a day. But today his back was not paining.He is also a patient of Cervical from many years. He also take a lot of stress. He is taking medicines of kidney stone and prostate. But today he was saying'Mujhe aisa chakkar pehle kabhi nhi aaya'. So what could be the reason? Is it serious? P.S- From last month he is drinking buttermilk and eating curd everyday. He is also eating 4-5 Guavas everyday. ( i mean can these things also cause dizziness)