It is not uncommon for medication to cause a significant increase or decrease in weight that's completely unrelated to diet or exercise and which may be unlikely to respond to a change in either. I agree you should discuss this or any other side effects with your doctor.
Lynder, my dr put me on Lexapro in January and I gained 14 lbs. some meds do cause weight gain. drugs for anxiety cause weight gain.
since you do have another medical problem you really should check with your dr to see which plan would be ok for you.
I m on atkins and hve lost 15 lbs so far . Im on a lot of other medication but my dr suggested for me to cut down on all my carb intake so thats what I have done. mainly given up all the junk food and pepsi that I consumed every day. I feel a bit run down but I walk a lot and Im sure that this will improve.
good luck to you.