Hey guys, I've been having an extremely rough spell lately and I was wondering if someone would help me?

See my CRPS has spread from my right leg up to my right arm, so it's been hard. My doctor didn't believe me, although I know it's there because of the pain and ice coldness. Also, my back has been real painful too. And I tend to cry a lot because of it because I don't know how to express the pain I'm in. It's really hard being 15 and having trouble with friends, family, school, and this pain at the same time.
So I've been turning to my boyfriend to talk to. But lately, he's seemed distant. Like he didn't wanna talk about it. He said he doesn't like to hear me complain about it all. Which he still listens but when I talk about it, in the back of my mind I know that he's not wanting to hear it. I know he cares but, still.. know what I mean? He means a whole heck of a lot to me and I really would like not to lose him. We've been together four months now and he's the first guy to ever care for me and take care of me, he even helps get my medicine and put my boot on and off my leg. He carries my backpack around for me and he holds my hand and hugs me and tells me it's all gonna be okay. He's given me a chance when noone else has, Logan's given me hope that there are people out there that love me for me, despite my being different. What's a good way to strike up a conversation about everything, is there a way to tell him that I don't like to complain, but I do need someone there for me since my mom thinks I'm just overreacting a lot of the time? (that's a different story) And is there anyway that I can try to keep my attitude more positive so that I can make everyone around me happier?