If your used to a normal European mattress, medium to soft, a Thai mattress, hard to rock hard, can take some getting used to and initially bring on excruciating back pain, get a memory foam topper, do some excercise, walking is always good, apply liberal amounts of Volteren and take some pain killers, not opiates!!
You can’t be serious about going back to UK for medical attention, you’ll wait 3 weeks for a GP appointment, assuming you can get through on the phone!! Then you’ll jump through hoops seeing a variety of specialists, starting with the least expensive option, then if you need surgery you’ll probably wait 3 years, after which you’ll be discharged after a day and left to fend for yourself no matter how incapacitated you are!! Forget it, stay here!! Go back there, dead within a year!!