I get tremors in my chin that lasts only for a second. Is it something serious?

Hello doctor,

I am 25. Since three days, I have been experiencing sensations like twitches/ jerks/ tremors specifically in my chin area. I noticed that when I talk, eat or when something falls down from my hand suddenly, I get a tremor in my chin. They last for a second only. I went to a doctor (not a neurologist but an internal medicine specialist) and as per him, I have a B-complex deficiency and he gave me 30 tablets of B-complex. He feels that the tremor while talking or eating that I face is coincidental. However, he did tell me that if I was very anxious we could get an MRI done. Apart from this, I also get mild muscle twitches in the eye, face, and legs. And sometimes, I feel a shortness of breath and when I get very scared there is tightness in my throat. I actually read a lot about this on the net and to be very honest, I have become very scared after reading about brain tumor, multiple sclerosis, etc. I wanted a second opinion. My doctor said I am otherwise very healthy so I should just take the vitamins and focus on my work and other activities. But I cannot stop thinking about brain tumor and other neurological disorders. Should I get an MRI? Or is this something that is not serious?

Please help.