Thanks for your question on Health Care Magic.
I can understand your daughter's situation and problem.
By your history and description, she is mostly having
obesity hypoventilation syndrome (OHS).
It is seen in patients with
morbid obesity.
Due to morbid obesity, when this patient lie down, excess fat tissue in neck compresses trachea and cause sudden stoppage of air and hence patient arouse and gasp fir air.
So you should definitely consult sleep specialist and get done sleep study for her.
Sleep study is must for the diagnosis of OHS.
For her weight gain, better to get done
thyroid function test, sugar levels and
lipid profile as alteration in these can cause weight gain.
So consult sleep specialist and discuss all these.
Hope I have solved your query.
Wishing good health to your daughter. Thanks.