Suggest Treatment For Hyperthyroidism

My thyroid levels remain high after lowering my thyroid medication every 3 months going from 150 mcg to 125 mcg and just started 100 mcg yesterday. More lab work in 6 weeks? What symptoms do I need to worry about? Does the fact that my generic thyroid meds are manufactured by different drug companies and may change additives in the pills which render effects of the meds ineffective?