It's 4:27am and I've not yet been able to sleep. I have given up trying for a bit, to vent and pontificate about chronic pain. By sharing my reality, I hope to help people understand it (as trite as that sounds).
There have been times I've experienced such acute pain that I've presented to medical types and literally begged for help. I've been able to stand, while explaining that I'm in some of the worst pain I've ever felt, and lay still while they examine me. My heart rate does not pulse fast, I don't sweat, nor do I roll around and moan or cry.
Doing any or all of those things (or none!) are a perfectly valid way of expressing how you're feeling.
As with many people dealing with chronic pain, I find that I just don't have the energy to express it loudly, or outwardly. So when I say to a medical type person, I'm begging you to help me find some relief, and then pass out on a hospital bed two hours later, I'm still valid. It still hurts. I still need your help.