I am not currently on methadone but have been in your shoes before, my friend. First, none of this is medical advice, I'm just sharing my personal experiences and thoughts.
At one point in time when I was going to a methadone clinic, I had tapered from 80mg down 2mg without issue. I was going down pretty slowly, something like one milligram a week or every other week. Anyways, I felt I was being ripped off as when I was at 80mg I was paying $100 and now that I was 2mg I was still paying $100 a week. So I decided to jump off and quit at 2mg. In all honesty, I felt as sick as when I had jumped off at 25mg on a previous occasion. Everyone reacts differently of course. Methadone is a bit trickier to detox from since it has a tremendous half-life (meaning it stays in your system for a long time). Long half-life means long withdrawal. Some of your organs become saturated with methadone when you're on it for a long time which can complicate things.
If I were you I would definitely discuss your troubles with your doctor. Maybe you need to bump your dose back up or maybe you need to stay at 1mg longer until you feel ok. However it goes down, I wish you luck and hope you feel well and avoid any withdrawal.
Peace