"Hot Water Bottle" is AFAIK a UK-centric term. Also rather large, and perhaps too visible.
A possible alternative:
I use "Hand Warmers" (for warming muscles) that contain a liquid when ready to use, and have a simple mechanism that changes it to a soft solid form that's quite warm (maybe 70% - a bit to hot for me to have directly on my skin (except for e.g. hands).
They "recharge" via boiling them for 15 minutes or so.
My largest is 8x13 cm, but the tech is very simple (it's just a liquid with convenient properties). I don't see why they couldn't be made much larger
Mine have text "KAYOBA" on them - probably the manufacturer.
Also if you haven't looked at your diet, you should.
Many things can cause that issue, and diet doesn't help in all cases. But it's like drinking water when you get a headache. It might not help, but it's cheap, fast, easy, and is effective surprisingly often
A possible alternative:
I use "Hand Warmers" (for warming muscles) that contain a liquid when ready to use, and have a simple mechanism that changes it to a soft solid form that's quite warm (maybe 70% - a bit to hot for me to have directly on my skin (except for e.g. hands).
They "recharge" via boiling them for 15 minutes or so.
My largest is 8x13 cm, but the tech is very simple (it's just a liquid with convenient properties). I don't see why they couldn't be made much larger
Mine have text "KAYOBA" on them - probably the manufacturer.
Also if you haven't looked at your diet, you should.
Many things can cause that issue, and diet doesn't help in all cases. But it's like drinking water when you get a headache. It might not help, but it's cheap, fast, easy, and is effective surprisingly often