What should I do if I send too many text messages and my thumb hurts?

The problem of mobile phone keyboard, when PHS sends short messages for free, I send hundreds of short messages to my classmates every day, get up in the morning and brush my teeth until I go to bed at night, and my fingers don't hurt.

So it should be that your mobile phone keyboard is too hard or the keyboard layout is unreasonable. Change a mobile phone with a comfortable keyboard.