What to say when you feel a pain in your body

بِسْمِ اللہِ

In the Name of Allah.
The Prophet ﷺ said: Put your hand on the part of the body that is in pain and say “Bismillah” three times: And say seven times.[Next Dua]

[Sahih Muslim – 2202]

اَعُوْذُ بِاللہِ وَ قُدْرَتِہٖ مِنْ شَرِّ مَا اَجِدُ وَ اُحَاذِرُ

I seek refuge in Allah and in His Power from the evil of what I find and of what I guard against.

[Sahih Muslim – 2202]