Suggest Treatment For Hypothyroidism Caused After Taking Tablets For Hyperthyroidism

G/M HAVE been underactive throid for 20yrs been on thyroxine last 22/10/14 taken :ow 50mcg blood test11/03/15 TSH was0.43 L (0.50-5) So the GPstopped my throxine altogether, after taking it for so long IM anxsiou, appartley i have too muck throxine I gather, 20yrs ago Iwas overactive thyroid, had tablet to lower then came underactive, what should i do please