What could cause episodes of all day bothersome dizziness in the head (no vertigo or spinning) &lightheadedness & then followed by entire inner head pressure or pressure at back of head and squeezing sensation at neck. no headaches?

If an examination reveals no medical issues,I would attribute your symptoms to excessive nucchal and scalp muscle tension, most commonly caused by chronic tension & stress. Treatment with massage therapy and stress management coaching should help if you think this pertains to you. I assume you have a good pillow which is important for relaxing neck musculature.