My mom wakes up some days feeling her head is heavy and when ever she puts her head down her head and eyes hurt. This happens between every 3 days. Why?

Sinus pressure? This symptom is consistent with sinus congestion or pressure, as it can be sensitive to head position. Since there are sinuses all around the eyes and orbits, this might seem like aching from the eyes or behind the eyes. Cervical spine problems can also cause referred pain to the ocular area. There are eye conditions that could cause this, but they usually are not so intermittent.