Struggling with Chronic Pain and Lack of Medical Support

My pain doctor has kept me on meloxicam for over 3 years now and I’ve been having extreme pain, but we literally get one appointment a year. He tells me to exercise more and get in the sun more, try more physical therapy and doesn’t help, but he’s the only doctor in my state, and I still have ~4 1/2 months until i turn 18 & age out. I try to exercise as much as I can and get in the sun. I have a bit a trouble breathing if I’m moving too fast or if I’m overheated and/or in pain. I have an inhaler as well. Considering the sun, my body has a reaaaallly hard time regulating temperature and i get this sort of heat rash, like firey itchy red skin all over my legs, arms, my whole torso & my forehead. It takes extremely long for it to go away even when I’m wearing the proper clothes for the weather & still sweating horribly. I run around at work I’m not extremely fast but I do have stamina and a good work ethic. I’m not by any means inactive. I walk in school & up stairs multiple times a day although i do have an elevator pass which helps me go up 2 floors since it’s a school in the middle of the city & has a lot of stairs & quite a few large landings/walking spaces thatre a bit spread out & groups of kids standing in the way during a pandemic. 😭 lately my back pain is getting worse and worse every single day and my mom still tells me I need to move more, but genuinely sometimes it really doesn’t help but sitting does hurt as well, i cant find a comfortable way to work lately, my back is genuinely hurting me so badly. I’m at a loss for what to do and they make me feel crazy🥲