Natural colon symptoms and conditions

I have been using MiraLax for 3 months now. It has helped me tremendiously with my constipation however I have had horriable gas
and bloating I have gained 10 pounds. I am a regular exerciser and weight liftter (toning mostly) . I could not figure how I gained the extra weight. I hav'nt done or taken anything different except taking the MiraLax. I was told it did not make you gain weight or give you gas. Maybe all the studies are not out yet. I don't know but I need to get this weight off fast. Could it be water weight?? from miralax? Please if anyone who has used Miralax or a doctor who has had this problem help. I hate to quit taking Miralax because it really helps me. It has been the best thing I have used in years. I would love anyone to comment or offer advice.