My sympathies on your pain,.. I put my back out 2 weeks ago and couldn't even walk,.. luckily the tablets worked and I'm now back on my feet and working, but I have a newfound sympathy for those who suffer from back pain, it really is debilitating.
I would contact all those who are overdue and explain the situation, saying that you're getting someone in to look after the work, but he may be a few days late,... then its time to find a man who is reliable, experienced & trustworthy,.. not an easy challenge at times! Phone the local cleaners, see if any of them can help out, and maybe put an ad in the local paper for a worker?