Welcome to HCM,
If any one gains weight rapidly and have associated symptoms with high TSH
, first thing which comes to mind is possibility of Hypothyroidism
which may be sub clinical.
But we should keep our mind open to other possibilities also such as metabolic syndrome
,simple Obesity and other hormone disorders (Diabetes
, Cushing's syndrome ),even swelling all over the body related to kidney
In such case a good physical examination with appropriate investigations will help to reach conclusion what she is having.
Please have faith in your treating Physician and follow his/her advise as doctor will try level best to diagnose and treat patient in most appropriate way.
I hope nothing serious is detected.
Please take care of her