Tremors with blackout of eyes. Steps.

Hi, My husband usually has mild tremors in his fingers when he is in a hurry or when he is tensed. Example: while getting ready to office. Very rarely he is getting severe tremors which makes the whole hand shiver or shake for few mins. During the same time vision is blacking out. I immediately gave sugar and he was normal in sometime. There was 3 hours gap after an evening coffee. And he was continuously doing some chored that made him sweat after which he got this tremor and eye blackout. His blood tests are normal. An year back master checkup was done and that was also normal. Only relatable thing is his Father has tremors. The severe tremor with eye blackout and feeling like fainting off is scary. Kindly suggest next steps.