Phone won't fast charge

Hi. For a while now my phone won't fast charge, it takes 8 hours. For some reason though. I plugged my phone charger into a USB outlet in the hospital and it worked fine. I've tried my wife's charger, didn't work. Tried my phone on her outlet, didn't work. Yet her phone charges just fine on all the chargers and outlets I use. I am completely baffled as I feel I've tried every combination of things that could have gone wrong. Thanks in advance