What do you do if you can't stomach changing the dressing on your child's wound?

My son crushed the tip of his index finger in the door at school. We went to the ER and he received 10 stitches. I'm usually okay with most of what I see, but he really did a number on himself and its pretty gory. I changed the dressing on Sunday, and nearly ped out! When I say nearly, I really mean it! As soon as I looked at it I was having hot/cold flashes, my hands were shaking, got dizzy and extremely nauseous. I'm not sure I can do it again, so what do I do? My son is already nervous about how his finger will heal, and seeing me that way just makes him more nervous, not to mention that I have to have my younger son keep him from looking at it, because if my son looks at it, he's going to panic! Dad is out of the picture totally, so there's no help there, and my family lives nearly an hour away. If I bring him to the doc to have it changed, will they charge me for it?