My sister is doubly vaxxed and thrice boosted, and she gets sick all the time, too. She got CoVid last Fall, and while it has been mild, she has had energy issues, and cold-like symptoms off and on for about 6 months now. Before she got CoVid, she had other colds and viruses since she got her first dose of Pfizer. Within a week of her first dose she had swollen lymph glands in her neck and mouth. She was very careful to not go out in public at all, and wore a mask (still does) anytime she goes out of her home. Her hands look like she has rheumatoid arthritis but she said her doctor has checked that and that’s not it. So I guess she has to live with her decision as well.
Your sister’s case sounds VERY similar to my aunt’s situation.
Doubly jabbed, double boosted....she had been in fairly good health (just celebrated her 80th birthday), minus the swollen lymph node issues in arms/neck that she got after her second shot...still got boosters 🙃...until a couple of weeks ago.
She had a sore throat and chest congestion....that kept getting worse...went to ER....tested positive for china virus....was put on paxlovid....and, is gradually getting better, each day (again, this has been two weeks, this weekend). Has ongoing fatigue, that will hopefully subside.
She told me she has to wear a mask, everywhere she goes, per docs orders, for another two weeks.
🙃 🙃
I hope she and your sis improve.