The fall in hemoglobin could be indicative of blood loss somewhere in the system, could also be lack of B12, iron loss. etc
Perhaps you should be checking with the doctors about it all.
An increased ESR can be due to inflammation it is a non specific test.
Has a CRP been done also?
So sorry that Sarah is going through this bad patch and hope she will be better soon.
Hugs and best wishes
Trysha