I had a tooth pulled on Eruv Shabbos and the dentist advised me to use an ice pack on Shabbos to keep the swelling down
He provided me with a freezer pack with water inside which i must freeze on Shabbos and then take out to apply to my jaw to keep the swelling down
Is this permissable?
There is controversy if it is permitted to make ice cubes on Shabbos. If however it is a big need for it on Shabbos numerous poskim permit it. If you need the ice to reduce swelling, that would be considered a big need.
Maharshag 2 103, Shevet Halevi 3-55, Shmiras Shabbos Khichoso Chapter 10-4, Orhchos Shabbos Chap. 4-52.