How Would You Handle Your Kid Being Bullied

My 15 year old son is being severely bullied. He's being called names. A girl put gum in his hair and he's gotten spit on. My kid says whenever he tells a teacher they just make the kid apologize and that's it. We went that something similar with my daughter at the same school. I was up there every freaking week. Nothing happened until she finally punched back. SHE got suspended. Should I even bother going up there Monday or should I just pull my son out and homeschool him. It'll be easier with his medical condition, he will always have a bathroom. However I also want him to have social skills because he told me he doesn't have any friends. I'm not saying homeschooled kids don't have social skills... Just that he already keeps to himself because of all the bullying in public school. I really want him to make friends. He seems so lonely.