Feeling Like I Could Die Any Moment

tw feelings/thoughts of dying (not suicide) ive noticed this thing going on for the past few years where i feel like im about to die/like i could just stop trying and give up. it feels like i could just stop breathing and fall to the floor dead if i just stop trying to survive. it isnt a panic attack, because those make me feel like im physically dying in the moment. this feeling is more like "i am okay right now, but if i stopped trying i could die right here and now." It's so hard to describe. it's like i can feel every aspect of my body struggling to continue functioning and my brain is tried of keeping everything together. i just want to let go and unwind like a ball of yarn. it also isnt about suicide. i dont *want* to die anytime soon, and whenever i get this feeling im afraid to relax too much or my heart will just stop. unsure if this is a dissociation issue, a trauma issue, or a physical issue.