It seems like you're holding the pressure in your head instead of holding it in your abdomen. If you feel any pressure in your head/ears at all while squatting you need to re-evaluate your breathing. You want to hold the pressure solely in your abdomen and squeeze. The purpose is to keep your core as tight as possible, giving yourself the most support possible.
Try pushing down into your belly/abs and close your throat tight. I know, it sounds tough - experiment a bit. When you get it right you'll know.
Also, there's a good trainer I watch a lot on youtube, look up "Strength Camp squat breathing" This should help you more than I could - good luck!