Thyroid TSH 50. Energetic and active!

Hi, I want some advice for my mother. She is having thyroid since last 30 years right from my birth and it is on level only with medication. Last time she checked it was 10 and this time she checked after 2months now it came to 50. She takes eltrocin 50 and previously she used to take eltrocin 100. Her thyroid is always on the higher side.. but whn her thyroid came down from 30 to 10 the doctor decreased her dose to 50mg. Recently she started having nausea, drowziness, throbbing headache and overall pain so she got tested her thyroid and the result came as 50. I'm extremely worried what is to be done. She also has some mental health issues few years back and prescribed Stalopam plus and she is taking that for 4 yrs now. She is extremely energetic and active