Single dad here, having a really tough time with my son and seeking advice with his behavior

Hey there, a little background. My son was born overseas 5 years ago and around his first birthday I got a visa for his mom and they both got to come to the US. I went back to school, but things weren't working out with his mom and she left us both when I was a junior. I managed to finish school as a single parent and have secured a good job, but my son's emotional development kinda paused when his mom left. She hasn't visited in about a year and he is struggling with that mightily.He goes to weekly counseling, but at the school where he went to preschool we were basically asked to not come back for kindergarten due to his behavior, and now that he's been at a new school for kindergarten his principal already wants to meet with me about his behavior.At home he is usually wonderful, but occasionally he has sudden, awful mood swings and commits a lot of "attention seeking" type issues: saying bad words when he's angry, refusing to eat for long periods of time, telling me he wants to leave and never come back. He cries almost every night before bed asking when I am going to get him a new mommy, and sometimes while grocery shopping he asks strangers if they will be his mommy. I had to move back into my mom's house recently so I could have some help getting him picked up from school and to help her as she goes through some medical issues, and he begs her to let him call her mommy. The kid is clearly struggling.His issues at school so far seem to circle around misunderstanding social cues and boundaries: hugging, pushing, etc. Friday I was informed he jabbed another kid with a pencil. He told me he was showing him where his grandma's IV is, his teacher described it as "stabbing." Now the principal wants to meet with me. His last school used to complain about the same thing, that he didn't understand boundaries and ignored social cues if they inconvenienced his impulses.To clarify, he has been tested 3 different times to see if he is on the spectrum and all 3 times I was told he shows no sign of it but does have some eccentric behaviors I should keep an eye on, like answering questions indirectly (Question: Is this box a square? Answer: It is not a circle, triangle, or hexagon.). I want him tested for ADD or ADHD, but I fear it could be something deeper. Academically he excels, all of his school work is great and he is on pace with the rest of his class. And usually it is only in the afternoon that he has issues, after behaving perfectly fine in the morning. This is the same both at home and at school. This led me to believe it could be dietary but dietary changes have not noticeably helped.Running out of options here, he is a smart boy. Super affectionate and sweet, goes out of his way to help his grandma. He is my world and I want him to be happy and do well in school. But he seems to have no impulse control and acts out often. I don't want him getting booted from kindergarten, right now I am just checking my phone over and over hoping there isn't a message from his teacher. I just want him to make it to Wednesday at this point.Anyone else gone through this and could help? I tried searching around and couldn't find anyone going through the same situation via /r/Parenting https://ift.tt/2mkOJQ1