Check your rear axle is tight and both chain/wheel adjusters are nipped up tight. Are both suspension units on the same setting and the rear wheel free from grease. Get someone to hold the bike steady on its side stand with no weight on the bike and try and shake the back wheel.
Your looking for lateral movement here from bearings, either wheel or swinging arm.
If you can raise the wheel enough to spin it, is it running true or damaged?
If all this is ok it’s just in your mind.
Last edited by hombre; 01-25-2019 at 07:53 PM.