In long standing hyperthyroidism
your body is used to the high T3 levels which keeps your mood in hyperactive anxious state. Once it is brought down by carbimazole
you may feel little depressed or moody.
If you are having persistent symptoms you may consult your doctor who an help you with some tranquilizers.
Hope I have answered your query. If you have any further questions I will be happy to help
With warm regards,
Dr Ajish TP (MD,DM)