★★★★★
My first thought was plantar fasciitis since his dad and grandmother have dealt with this and many in my family have pretty flat feet. He is on his feet all day (forestry and farming work, so at least not concrete.)
I bought him a pair of insoles with an arch support for under $10. He put them in the shoes he wears all the time.
A few days later he realized that he had no more pain!
So happy for a cheap solution for him!