Coping with chronic pain/illness

I've had a lot of issues with POTS (postural orthostatic tachycardia syndrome), chronic pain, fatigue, and more along with mental issues. I was only diagnosed with POTS very recently, which it has been a bit of a help to have the diagnosis because I am better believed when I talk about my issues and I have a bit more access to help. However it has also been incredibly hard, I only got diagnosed because my symptoms have gotten increasingly worse (main thing that led to actually being believed and getting the diagnosis was fainting at school) and I'm not sure how to deal with it, I have terrible pain in my hands and legs almost constantly, I can't stand without moving a lot for more than maybe 10-15 minutes or else pain becomes worse and I get very lightheaded. I'm trying to work with people to make life feel liveable again but the pain alone has become almost unbearable. So that's why I'm reaching out here, I'm open to any ideas to help cope mentally with it all as well as any sources of pain relief.