Welcome to health care magic!
I have read your question and found that there is weakness in both arms, along with some visual disturbances in which you see colorful speck on and off, and shiny patches.
Your symptoms need a through check up, preferably by a neurologist
as symptoms suggest some problem in Central nervous system
Had I been your treating doctor, I would go for an MRI
brain along with routine blood teats, and Blood pressure recording. An opthalmological check up, like fundus will tell about brain pressure/oedema or any eye pathology which might cause these specks.
You have not mentioned anything about the duration of illness and yor age, so, it becomes rather difficult to say much.
Visiting a neurologist would be good for you.
Hope that you get better fast.
Please feel free to ask more questions
Dr. Manisha Gopal