Where do you live? I’m in a rural area and there is a village support group for exactly those sorts of emergencies. Listed in the parish mag, they are volunteers with lots of contacts, who provide a bit of backup when needed.
Or try the children’s centre or talk to the practice manager at your GP. You aren’t the only one with no family support. Have you asked your son for suggestions? 13yos can be very resourceful and he may have some ideas.