My mother-in-law gets a kidney infection every time she travels, Max hasn't been drinking enough water!
They are very painful, hope she is feeling better soon
One of my housemates during my study years had a double renal pelvis infection. She postponed it, but in the end she was in too much pain and discomfort that she went to the hospital. Well, they immediately kept her there. After several days she was allowed to go home, if I am correct the doctor would have liked her to stay a little bit longer. She had to rest and don't overdo, it was the best if someone could take care of her. In my memory she was in a lot of pain (was even painful to see) and took it a long time for her to become her old self again.
We learned that one of the measurements that can help is the intake of sufficient amount of water (fluids).
If I am correct the renal pelvis infection can also be a result of a neglected urinary tract infection.