Horrible shaking and wobbling

[bop12]

Hi,
I hope I finally found forum where I can find answer for my problem
I have Chinese scooter Maxon Matador 125 (GY6). Scooter is approx 4-6 years old and have any 1500 miles.
When I ride around 30-35kmh it starts shaking and wobbling really hard. I can barely see something in my mirrors. My hands are like under 10kilo volts..
What could be issue?
Additionally, my maximum speed is about 40-45 and it shouldn't be problem as far as I read, to reach 50-55 mph.
Could you please help me what to check?
Thanks a lot!