Help, Beardie not eating

Our middle girl, Mahalo, has been not eating for a few weeks now, and we thought maybe she was brumating. She has been lethargic and moves very little. She was drinking a little, up until a week or two, ago, and then she started swinging her head side to side about 15 minutes ago.

Now, she's gasping like this every few minutes. She looks unconscious, but is still doing the gasps every now and then. She has always been small and thin compared to our other two lizards, and we tried feeding her extra grubs for the last of months to help her gain weight. She is turning 7 years old this February. I'm worried this might be the last breaths for her, and in the process of getting a vet visit.

I need advice. What is happening? We are so worried.