Methadose and cravings

I HAVE BEEN ON METADONE FOR ABOUT 7 MONTHS NOW AND I AM UP 150 MGS A DAY, I HAVE FIBROMYALGIA AND THE PAIN IS JUST TERRIBLE MOST OF THE TIME, WHEN I FIRST WENT ON THIS DRUG I THOUGHT THAT IT WAS THE PERFECT DRUG, IT TOOK ALL OF MY PAIN AWAY, IT WAS SOMEWHAT CHEAP, AND MY DOCTOR WOULD GIVE ME ENOUGH OF IT TO TAKE CARE OF MY PAIN. HOWEVER ...I WAS ALWAYS A SMALL WOMAN THE MOST THAT I EVER WEIGHED WAS 150 PONDS AND THAT WAS WHEN I WAS 9 MONTHS PREGNANT WITH MY CHILDREN, I USED TO HAVE TO MAKE MYSELF EAT TO TRY AND GAIN WEIGHT..AFTER BEING ON METHDONE FOR ABOUT A MONTH I STARTED TO NOTICE THAT I HAD INTENSE CRAVINGS FOR SWEETS THAT I COULD NOT DENY...IT WAS LIKE NEEDING A HIT OF HERION OR SOMETHING.. NOW THAT LITTLE GIRL THAT USED TO HAVE TO TRY TO GAIN WEIGHT AND WHOS NORMAL WEIGHT WAS 115 POUNDS IS UP TO 162 POUNDS AFTER JUST 7 MONTHS ON THIS DRUG, I AM ONLY EATING ONE MEAL A DAY AND JUST HAVING A FEW BITES OF SOMETHING AT BREAKFAST..THE MORE I TRY TO DIET THE MORE WEIGHT I GAIN...SOMEONE HELP!! IS THERE ANY THING AT ALL THAT I CAN DO .. I CAN SOMEWHAT DEAL WITH THE CONSTIPATION THAT IS NEVER GOING AWAY AND I CAN DEAL WITH THE SWEATS THAT ARE HORRIBLE - I CAN EVEN DEAL WITH THE SLEEPINESS AT INAPPROPRIATE TIMES BUT I CAN NOT DEAL WITH ALL OF THIS FAT..THIS IS MAKING ME EVEN MORE DEPRESSED AND SUICIDIAL THAN I EVER WAS BEFORE METHADONE....I REALLY AM THINKING ABOUT TRYING ANOTHER DRUG BUT THEY ALL JUST COST SO MUCH.....ANY ADVICE FOR ME ABOUT THE WEIGHT GAIN???