Physical pain is a signal in your brain telling you to stay away from electricity, sharp objects, and fire etc. It also tells you when something important for survival is absent like food leading to hunger headaches.
So basically all physical pain is caused by you (the brain) being attached to survival.
Physical pain has a huge emotional component. That's why we can train pain tolerance. Placebos and holding a loved one is sometimes as effective as morphine in reducing pain.
So all in all suffering is due to attachment. If you let go of the attachment by training your mind you can end suffering.
Not necessarily. There can be meaning in suffering. You learn and change through it. And sometimes that's a positive change.