Onve you have reported the lost passport to police and applied for the emergency passport from.the embassy, your old passport is automatically canceled so there's no benefit to finding it.
Emergency passport should last 6 months, no reason that you have to leave because of that. I was in the same situation and continued my holiday on the emergency passport.
A good chiro can work wonders I have chronic L4/L5 pain and used to go to chiro once a month as a maintenance measure. These days however I find the best thing is - drink lots of water (so simple that people don't bother to do it... hydrates the disks preventing pain), lots of walking, lots of swimming and yoga stretching. The more pain I have the more I force myself to walk it off until it loosens up. Use a walking stick of you have to. The worst thing to do in this case is to sit on the couch. If the pain od unbearable try a balm or topical pain killer applied to the skin. All the best.
I have seen some facilities set up for foreigners. Looks like you would receive a much higher standard of care due to low staff costs. Of course the downside is you may be far from family and friends unless they are in Thailand already.
You don't need to support your family because they are well off. Most thais do have to support their extended family. Your experience is not typical of most thai people.
My wife is Chinese Thai also from the south. No dowry she is university educated. One does not buy a wife in western culture but looks after her well. I am Buddhist as well as my wife but I do not automatically let thai culture always dominate over my own.