Behavioral problems

Okay so my son has had temper issues we'll say for a couple years now and the older he gets the worse it gets. He doesn't want to help clean or do anything that he thinks is boring. He has been having a lot of issues in school lately. Telling teacher's he doesn't have to listen. Hitting other students (only happened once). Not doing work. Running around the classroom. Listening seems to be the big issue though. He throws tempers if he doesn't get his way (and no I don't give him what he wants for doing that) and it's honestly becoming so overwhelming because I'm a single mom and his dad doesn't seem to care. I honestly feel like my son has ADHD or some other behavioral issue because it's only getting worse. I try talking to him about it and when I ask him why he doesn't listen to the teachers he says he tries it's just hard and that it's hard for him not to be angry. Does anyone's child have ADHD? I don't know what else to do because his doctor won't listen to me and she jots it down to his age but there is definitely something else going on. What can I do to help him focus more? Is there anything I can do? He just turned 6.