It sounds like your doctor might not know a lot about
Armour - first off,
synthroid is prescribed in mcg;
Armour is prescribed in mg. Synthroid is a T4 only med, Armour has both T4 and T3 and contains much more T3 than humans, typically, produce. Additionally, T3 is fast acting and doesn't stay in your system very long, so it does need to be split into multiple doses i.e usually 2, during the day in order to keep FT3 levels stable.