Benadryl broke my brain and reality is not the same to me anymore

About a year ago I was diagnosed with cancer, but believe it or not this is not what the story is about. A part of my treatment included a really weird drug that the body doesn’t tolerate very well. The way they combat this is by giving you Benadryl before taking that drug… like a lot of Benadryl. So I walked into the treatment centre with my dad and sat in the recliner chairs they had, my dad sitting on a stool beside me. The nurse handed me my Benadryl along with some other drugs to prepare my body for the 2 hours of chemo. I took the Benadryl, put my headphones on and tried to sleep. I was playing a playlist of a bunch of Queen songs, and hoped that would take me on a journey. I had a weird dream, where I was sitting in the same recliner just watching everyone pass me by. I could see the nurses walking around and could hear them talking to other patients. The music I was listening to was now in the background as if playing on the hospital PA system. I saw my dad sitting beside me watching me, it was so surreal. At some point I saw him get up and grab a coffee and come back. It was like my dream was just what was happening around me and my brain was piecing together a reality that didn’t exist. It made me feel like the world as I knew it could simply just be in my mind. I woke up two hours later when my chemo infusion was done and looked at my dad. He looked at me funny, I said “what?“. He said, “you freaked me out, you really just sat there for two hours, you barely blinked”. I didn’t know what he meant, I was still piecing things together from the dream I just saw. I looked over and saw he was holding a coffee cup, like the one I saw him get. I realized this whole time that I wasn’t asleep and was not dreaming. That dream was literally just me sitting there blankly staring off into oblivion. I also was not wearing headphones and have no idea what music I was hearing.

(Edit for more context: just cause everyone is wishing me good luck on treatment, it went great and now I’m 7 months in remission, that was my first ever time on Benadryl during my first cycle)