CLKD, am I understanding correctly your DH has a urine infection? If so, and you may already be aware of this, in men of a certain age, a urine infection is often a sign of prostatitis. My hubby had this about 10 years ago and it was horrendous. In spite of ABs for 7 days, the infection got worse and he ended up with chills then pouring with sweat and his whole body was shaking all over in bed and he couldn't get warm.
The surgery was sending off samples every week and just re prescribing the same ABs. After about 6 weeks of this, we changed GPs prior to moving house and the new GP had to do a house call to us for my dad, who we cared for, (it was his practice). My husband mentioned his stubborn infection and it turned out he was very knowledgeable about prostatitis and recognised it as that straight away. He gave 3 courses of 3 different ABs and a month later all symptoms were gone. He told us he had one patient who'd had it for 10 years and knew of another who'd had it around 20!!
Apparently it's crucial if the infection doesn't go after 1st course, the right treatment is essential.
Don't want to alarm you but this GP said men rarely get UTIs unless STD or prostatitis.
Hopefully the AB will do the trick for your DH and if I've got the wrong end of the stick, ignore all of the above 😆