Has anyone ever had tons of weight gain while taking Singulair? I...

Has anyone ever had tons of weight gain while taking Singulair? I have been on this drug for about four years now and my weight has increased to more than 50 pounds of weight gain! I have a lot of aches and pains, leg cramps at night, insomnia, but the asthma has improved. I still get my once a year very bad attack with bronchitis, etc, but the improvement was great. I have had everything else checked out for my weird continued weight gain and everything is normal. So I am checking out this drug and one other I am on for thyroid. (No, it's not my thyroid, my thyroid tests are normal now). It doesn't matter what I do I gain weight. Just wondering if this drug is causing it. My doc told me it was the cause of my insomnia and suggested moving it to the A.M.. I am tired of this weight gain, and it is starting more physical problems, like my bad knees. I ahve always been active and my eating habits haven't changed. Dieting is not working either. Any suggestions? Anyone else gaining unexplained weight? Thanks!