Here is a sample prayer for a person who is in pain that you can use as a guide:
Heavenly Father,
I lift up my friend/family member who is in pain today. Please be with them and bring them your comfort and peace.
I pray that you would heal their body and bring them relief from their suffering. Please give them strength and courage as they face this difficult time.
I pray for their caregivers, that you would give them wisdom and compassion as they care for my friend/family member.
Please be with my friend/family member in a special way, and let them know that they are not alone.
In your holy name I pray, Amen.