Nissan Qashqai vibration between 50-60 mph

Check your wheels and tyres for any damage , bulges or excessive wear . Check for any play at wheels . If all o.k , get wheels balanced

I’ve already done all that

It helps when posting if you mention any work or checks already carried out .

Check engine transmission mountings and driveshafts for wear

All checked by a garage

Hope you get it fixed