The only way i can get rid of migraines anymore is to take an ice pack and place it at the back of my neck until its numb, is that harmful to my body?

No: Some people do find that application of ice to certain areas of the head and neck region can help allevaite or reduce the severity of migraines and other headaches. A conventional ice pack should not harm your body..

Safe: No, this will not cause harm, and this does work because you are indirectly affecting the greater occipital nerves which run behind both ears. Therefore, might make some sense in your case, to try blocks of these nerves from a skilled anesthesiologist, as this action might prevent further headaches.