Hi u/Coliexsunshine, super connection you're making.

YES, absolutely parts can cause pain in the body. They can cause all sorts of physical symptoms. I've worked with many people with psychosomatic issues stemming from parts, and IFS can make a big difference.

Speaking personally, I developed an intolerance of gluten as an adult and later met the part that was causing this symptom. I learned why it was doing this, and negotiated over it agreeing to relieve the symptom. Today, I can tolerate gluten much better than before working with that part. (Scientific talk: I think of this particular example as the part turning on something I had a genetic predisposition to, aka using epigenetics to communicate with me)

Often these parts are frustrated we're not hearing them, and they're trying to communicate something to us.

It'd be much easier if they could directly tell us, wouldn't you agree? But we have to set the conditions to make that possible.

Which leads to your final question.

As a starting point, you could begin a session asking to meet the part(s) of you connected to the physical pain. You would then ask the part what it's job is, and what it's afraid would happen if it doesn't send you that pain.

This can be complex work and if you're in physical pain, really affecting your quality of life. You might want to consider finding an IFS therapist to guide this, if you can afford it. A good directory is here: https://ifs-institute.com/practitioners