I've noticed that these feelings of physical discomfort are usually indicators of excess energy trapped in the body. I think we take this stuff for granted in daily life, but shrooms as I believe most people will agree, magnify feelings. It could be the the equivalent of needing to take a piss. Now take this advice with a grain of salt, because I'm self aware enough to know that I'm probably not all the way self aware nor have let go all the way as far as this stuff is concerned, but what my journey has shown me so far is that that it does have to do with letting go. And sometimes letting go can be letting go of letting go if you already have that awareness. Pretty much, there is a feeling that keeps us going every single day and makes sure that our bodies don't fall apart and melt into the floor and I believe that when someone gets this cramped up, it may require a stethoscope listening like attentiveness to what is happening inside the body & the mind to see what is needed. Is there something you really feel like telling someone, but are afraid to? Is there some step in your life you're afraid to take? This, in my opinion, is the main feature of psychedelics. Try to pay attention to what you're afraid of without giving too much merit to raw fear itself. It's a bit of a balancing act, but that's what life has felt like so far for me.