What is up with this mystery? your thoughs and advice plz

Hi guys, so After that incident I had with my bf where he, weirdly Ghosted/dissapeared from that big miscommunication we had back on his ''Grad day'' some time ago, he has called me from an unknown number a couple of times, and I only picked up once and he said ''hello''hello'' and I could clearly hear his voice, the thing is that this man had told me he was leaving back to his hometown in the states one month after he had graduated since he had to do some errands before living, but a couple of weeks ago I found out he was still here (Due to him calling me from an unknown number, I contacted the person who rents him the apartment, which by the way does not know me, and I acted Like I was looking for an apartment with the same characteristics as his floor,rooms etc, and she told me that ''a guy that studies medicine still lives there, and has been renting for a long time and that he has not left'' so I inmeddiately knew it was him).

And to make the story even weirder, 1st: his family members did not come and 2nd: my mom was talking with me the other days and had asked me, if my ex had graduated in the graduation ceremony of march and I said yeah ofcourse that was his grad day, and she told me that she had watched the whole ceremony on tv (in this country they televise the grads by universities) and she replied to me ''how weird'' and I said'' why? she said:'' I did not see him at all, while they were handing out the diplomas of the medical school section'' and I said what!!, that is really really weird, so now it stayed in my mind, if something bad happened to him and they did not allowed him to graduate for whatever reason. I mean he is still here and has not left. sketchy, what do you think about all of this?