Practicing with pain is a whole topic in itself, and you can actually find entire books on the subject. There is a distinction between the physical sensations you are calling pain, your thoughts about them, and the mental notes themselves. I'd like to suggest that instead of noting "pain," that you try more neutral words that point to the direct physical experience such as "pressure," "burning," and so on. Play with using a gentle and soft tone of voice. If you can't soften the tone, that's ok. The purpose of noticing the tone of the note is to become aware of the attitudes you have towards the sensations (in this case it's probably aversion), rather than getting rid of these attitudes. If you'd like to hear more instructions on this, you can listen to Session 6 of “The Basics” course or to Session 6 of the "Pro Tips with JG" course.