I Have Had Low Thyroid Since 1996. I Am Being

I have had low thyroid since 1996. I am being treated with Levothyroxine. I was low normal last time it was checked and my dosage with upped to 100 mcg. My nails started growing again and I felt better but after two months I am back to splitting nails and feeling tired. I am being treated by my family physician. should I ask to see a specialist in this field?