Ice packs will only harm the nerve endings if they aren't used properly - 20 minutes at a time and you have to give your body a break in between uses of ice packs. You can use them every couple of hours though.
There was no way I could even take a hot shower on a really cold day if I didn't warm the bathroom sufficiently - I'd spend the next two days trying to warm back up!! Hot tea combined with a handful of other things will make you more comfortable, but low body temps have a specific cause that needs to be investigated.
Most doc's - even LLMD's - don't know how to read the thyroid tests properly. If you have a low body temp, you would do well to investigate your thyroid health:
www.stopthethyroidmadness.com/