Hello, I Have Been Having Chronic Constipation For Years. I

Hello, I have been having chronic constipation for years. I find that if I don't take a laxative I seldomly go to the bathroom. I have Sjogren's syndrom and my rheumatologist suggested I go see a Gastroenterologist. I have my appointment yesterday but I am not sure I feel comfortable with the suggested remedy. He told me to take Medimucil everyday which I am fine with but he also told me to take 1 spoonful of Milk of Magnessia three times a day. This is going to be my cure for the rest of my life. Is it okay to take that much laxative everyday? He didn't ask me questions about my diet or anything. I just want to make sure I am not hurting myself more by doing this. Please help.