Talk with the clinic. Hopefully they will be able to help you get off this. Good luck.
Tel your clinic the time fram you have to work with they can make up a taper to get you off in time just know this will not be painless at least you havent been on it long do the best you can with the taper but withdrawals are inevitable going this fast get up to walmart and pick up a 3 in one vitamin calcium/magnesium/zinc and start taking 4 every mornig and 4 every night at dinner this will cut down on the withdrawals considerably it takes around 3 days to work
the real problem I see here is not so much getting off the sytuff but the post withdrawals after methadone will keep you sick for quite a wile after you stop taking it there is an energy crash thats debilitating and the lack of sleep will drive you mad....I didnt sleep for 2 mo and thats not uncommon see what the clinic says and good luck to you........Gnarly
Taper it as low as you can and then stop. They should help you at the clinic with the taper.