A Pineal cyst (fluid filled sac) is a growth with smooth sides that appear on or near the Pineal gland. It occurs commonly and usually small in size. Pineal cysts are mostly benign and so usually ignored. Treatment is usually required in rare situations where the cyst has grown in size and when it starts to hinder the functions of other parts of the brain. Sometimes it becomes symptomatic. Usually due to increase in size and pressing onto other parts of the brain. Symptoms range in severity from nausea, severe headaches, seizures to coma. Large cysts can also cause visual problems. I would suggest you to take these symptoms seriously and consult an another doctor.