Ego loss for me usually comes from a large dose and it starts getting really intense. Any problem I have in my subconscious mind will be thrown into my face. I will often talk myself in circles (in my head) and get to a point where I am almost freaking out. I don't worry because I know this is part of the trip deep down, but I'll get to a point where I think I am going to die, forget everything I ever knew, or be crazy. At the climax point, I let go. I stop thinking/stressing out about it all, and then bam, it hits, and suddenly all the problems I had are gone. All the answers I need are plain as day. I see myself as one with the whole universe. My worldly mind and body don't matter, I am connected to everything in the universe, and understand how it all works and my place in it.
Someone who experiences this can get caught in the part before the climax hits. Often people don't know how to let go, and when going too far too fast, they get stuck in a loop or onto negative ideas. It can be hard to work through the trouble inside you, especially if it's your first time and have no idea what to expect or feel. It's often scary and people react all kinds of ways when they are terrified. His reactions sound like this could be what happened to him, but I am no expert, just lots of experience.