I'm not particularly experienced with this yet, but am heavily insightful with these kind of things.

I've used psilocybin twice, as a venture into healing myself. The first time I did them I ate them. I was sick to my stomach the whole time. It only subsided when I chose to sit with "the pain" around my heart. The nausea for the first several hours was such a deterrent that I opted to make a tea the next time. I just had that 2nd, stronger experience two days ago. I do my sessions at night, with an eye mask, and with soft meditation music (any other music, even my favorite, is beyond overstimulating). I had "nausea" for 2 hours again, but had made enough efforts leading up to it that I knew it wasn't nausea. Every now and then, I would remind myself that it wasn't actually nausea that I was feeling... but what was it?

As the hallucinogenic phase passed, and I moved more into the "feeling" phase, I found that I was extremely confused. There was no time, there was nothing else (there has never been a feeling of connectedness for me). I was stuck in a single moment in myself that was outside of time. This is from our pre-verbal years (either in utero, or infancy). The "nausea" was actually the massive weight of UNBEARABLE EMOTIONAL PAIN. I knew what needed to happen. I'd known for nearly 6 weeks that this was going to have to happen. I needed my mommy. I'll be 40 this year, but knew that there was no way I was going to be released from this unbearable emotional pain until I made my mom come over and curl up behind me. I'm glad that she's alive and lives an hour away. It was late at night, but she did it. Through my experience, she got to see the depth of the extreme pain that she'd repressed her entire life. Generations of that pain (lack of knowing how to give/receive love, and the abuse she suffered) was imprinted onto my very young heart. Why I was sobbing, I asked her several times "how did you survive this pain?" (At this time in her life, she still does not understand the strength it required for both her and her half sister to break such an awful cycle. Neither of them beat their children. It does not mean that we are w/o damage, but we are blessed to have such strong mothers... even though our mothers can't see it.)

As I moved further into the space where insight and the medicinal experience overlap heavily, the nausea started to come back. I knew that I was supposed to tell her everything. I keep a tight lid around my family and none of them has been allowed into my life. Each time I would talk, the nausea would go away. I'd think to myself "Oh, I don't want to share that yet,", but the medicine was going to have none of that, and would send another wave of nausea until I would let the words out.

As "reality" came back, we went for a late-night walk and I continued to dish about existence. This is something I'd do while under the influence or not. Insight is a gift. Once my mom got back home... at 3am, she sent a message that she would never forget this. I gave her the single-most bonding experience with one of her children that she'd ever had. It was medicine for the both of us.

Now... to your story. Thanks for reading mine.

You took a very powerful medicine into your body. To me, it feels like an organism (larva) is trying to manifest inside me. It expands and contracts, but has to get through whatever is holding you back in order for it to metamorphose and expand itself for the butterfly that you really are. My first experience, the larva was "stuck" to the cocoon, right at the back of my heart. I was filthy inside and there was filth outside. I spent time cleaning my home and learning respect for space and things. On my 2nd trip (above), there was no filth... either in me or out. This made me happy, despite the rest of the pain. The organism trying to fill me up was able to do so more than before, but clearly showed me what was preventing it from expanding further. There was nothing in heaven or on Earth that was going to allow me to move past that point until I did what was needed.

For you, having a more visual experience, it seems as if the visuals were telling you that you don't get to see those things until you've purged. How nice of them to show you how to do it. Though there may have been actual physical nausea/pain, it's more likely that those were a physical manifestation of the gunk/energy that needed purging... the acid that was eating its way through you unless you rid yourself of it.
Diet can definitely play a part in that, too. But... it's likely that it was much more than just the food you were taking in was only a tiny part of what really needed purging.

As I recount my story to more experienced people, they respond with "that's the medicine". It's powerful.

As you look back on this trip, can you see that you were given homework? Are there things you need to do to prepare your mind/body/soul for your next journey? It's important to take the lessons being shown to you and apply them in this reality. It's part of respecting the medicine and what it's doing for you.

I hope some of this applies to you in some way and that you find it helpful. Good luck!!!