Extreme weight loss in short-term rehab. Is this normal?

My 85 year old mother had a stroke on 3/16. She went into the hospital that day, and thankfully there wasn't too much brain damage. She was kept there 4 days, released into short-term rehab on the 19th. When she was discharged from the hospital, she weighed 90 lbs. She's been extremely thin for years now, but at the doctor's the week earlier, she was 92 lbs. She's 5' 3" tall.

So she's been in rehab two weeks, and today I find out - not from the rehab itself, but from the RN at the assisted living community mom hopes to move into after rehab, who was there to evaluate her - that she is now 82 lbs.! She's unhappy there, doesn't like the food, and is supposedly a "choking risk," so is on a soft diet. There's no evidence that she's ever choked, either at rehab or at the hospital. The rehab's answer is to give her Ensure, which she hates and won't drink.

I'm in totally new territory with caring for my mother, the stroke, rehab. I'm 300 miles away. My father died on Feb. 16th; and after 54 years of marriage, my mother is in despair. That said, she tells me she's hungry all the time, but just doesn't like the food. But a 10% weight loss in two weeks sounds like starvation to me.

I'd appreciate any perspective more experienced caregivers can provide. Right now I'm so angry at the rehab I can't think straight, but don't know if I'm overreacting. I am going to call her regular doctor and tell her about the weight loss.