Hi there,
My mother has been diagnosed with lung cancer 18months ago, she has also been going through the same jerks. She is now in hospice as she is very ill, but this has happened over time, her jerks have come and gone, and yes she the same is not responding with her eyes open, but is very alert and aware of what is going on in the surroundings, however she sometimes does not answer any questions at times but just listens.
She takes morphine and then feels really tired as she is first in pain then is given a high dosage drug which tires her.
You have to just deal with these jerks, as they may at times become worse than normal, but go away after some time, but then they do return.
Hope this helps.