Very briefly... My horse is bedded on straw, no problems...
Occasional snatching of reins, more like a jerking movement than shaking...
Trying to hit nose area with leg, itching nose on leg.. stumbling....
Lack of concentration...
Most horses only have symptoms when being riden and not at grass...
Do talk to your vet about your horses symptoms and discuss with your vet what they might mean.. good luck.. hope it isn't headshaking due to an allergy...