my son is 21 and when he was a baby he had a severe kidney infection which caused damage to his kidney. This left with about 15% of the function in that kidney. at 5 years old he had a procedure to correct a problem with his bladder, which was allowing the urine to flow back into his kidney, and since then has been fine. about 2 weeks ago he became unwell, pain passing urine, pain in his flank, tired and with sweats. his doctor gave him a course of anti biotic but the flank pain, while it has eased, has not gone away. Should he be referred to hospital? how long does an infection take to clear and is it more serious because his kidney is already damaged?