Many theologians differentiate suffering from pain. I would say that you experienced pain when your grandmother died. It has its beginning and end rooted in our physical lives. You felt the pain of loss and grief because you will never see her again in this life. Suffering, however, has its roots in the spiritual world, in God. It is the recognition of the spiritual good for which God allows pain. It is painful to lose a love one. However, if you turn your mind and prayers to God, you can find solace and consolation. Your grandmother is now with our Lord, and her parents and loved ones which she lost along the way. You, also, now have another loved one who sits beside our Lord praying for you. The pain of death is ‘Goodbye’. The suffering of death is ‘Until we meet again’. If you turn your pain into suffering and offer it to God for the betterment of your own soul that you may one day be reunited with your grandmother in heaven, it may not lessen the experience of the loss, but can help you shoulder its burden and move to healing through the graces of our Lord.
Pain is meaningless. Suffering is a gift from our Lord to lift us out of the pointlessness of pain to something truly greater: Himself.