1st of all, all the moving IS most of the problem. Making new friends in school is not easy, not fun, & down right depressing. I was there. Started 9th grade not knowing a single person. We moved when I was in pre-school, kindergarten, 3rd grade, 5th grade, & 9th grade...
2nd, get him to talk to a counselor, not the school one. That made it worse for me, to be pulled out of class to go talk to the counselor. The other kids were relentless in teasing.
3rd, he's having a hard time making and keeping friends, or afraid to make friends because he thinks you might move again. Get him involved in extra curricular activities? Church youth group, sports, ymca, Boys N Girls club,...something and try to be involved in it with him.
He may be being teased or bullied. Find out. I don't know why you have to keep moving, but if you can make it work & not move until he graduates high school, I think would make things better IN YOUR SONS MIND.
With working full time, being the main income for your family, how much time do you get to spend with your son? Maybe he is lonely and wants your attention?