It could be that you're experiencing dissociation. When I get super overwhelmed, anxious, and/or stressed, I fall into what I can only describe as autopilot. It's very numb and detatched, my brain's way of protecting me from intense stress. Everyone experiences it differently but the fact that you aren't consciously anxious anymore when it happens leads me to believe that may be the case. I think it's also important to consider that maybe these are anxiety/panic attacks. Not all of them have to be trembling, can't breathe, fight or flight attacks. Sometimes they can manifest as the often forgotten "freeze" option. The shivering, tenseness, and pain are what make me think it might be this option, could be your body exerting pent up nervous energy. I get like that when people yell around me, I shiver and get overwhelmed, nearly cry. It might also be both at once! Maybe you're experiencing an attack and that as a result is causing you to dissociate. I think your first step should be to identify what is making you feel this way and work to either avoid it or find some healthy coping mechanisms to help manage the situation before it gets to that point. I don't know your full situation but this is what I'd say to look into. Feel free to DM me if you wanna chat about it 😊

I agree that you may be dissociating from the emotion/experience as a way to protect yourself. Emotions can be expressed somatically, so the sensations in your body make sense and are totally normal for you to experience; everyone experiences emotions differently mentally and physically. Sometimes, when I'm very anxious or upset, I numb out and like, I mentally know what I'm feeling, but I dont experience in my body.