Looking at purchasing a new pillow but unsure of the cervical type pillows? Try rolling a towel up and placing along the bottom edge of your pillow. When sleeping on your back this will fill the space between the back of your neck and the mattress. When sleeping on your side this will fill the gap along the side of your neck between your ear and shoulder and the mattress.
If you find sleeping improves over the course of the week with one of these sleeping position positions then consider buying a cervical pillow such as this example courtesy of Sleep Boutique.