Thyroid problems are notoriously difficult to diagnose, especially if perhaps a borderline case. I assume she's done a thyroid function test? I had hyperthyroidism which gave me severe symptons but it still took ages to diagnose (my doctor even thought I had a brain tumour). It was only after it got so bad and I ended up in hospital that a doctor there diagnosed it after noticing I had a tremour and no strength in my muscles. After treatment I ended up with hypothyroidism which has a totally different set of symptoms (weight gain tiredness, hair loss, foggy brain). My meds change up or down a little now and then but the symptoms haven't really ever gone away.

I hope your new work regime works well. The boys are also back at work now and do three days; Monday, Wednesday and Friday which suit them.