Possibly stress. I answered a question recently re kids and blinking eyes. Same info holds true for adults. People get into habits (nail-biting, nose-picking, blinking, other tics) as stress-relievers. If the eye exam is normal, most often stress or exhaustion or habit is the cause. Rarely there can be central causes (blepharospam, etc) that require neurological evaluation, possibly imaging, sometimes botox..
Probably. Or dryness, allergy etc. Try some otc artificial tears/allergy drops and see an ophthalmologist if no better.