I would suggest seeing a doctor just in case, but I get chest pain as well, right in the middle of my ribs and also right under my left breast. Laying down makes it worse too, and it can hurt pretty bad. It is a part of the lupus and it is costochondritis for me. BUT, you should still tell you doctor about this. As for the twitching, I twitch too, in my legs because I have a pinched nerve in my back, and just in general everywhere else. I don't know why, but it just happens.
Ask as many questions as you want, that is what we are here for, to try to help you as best we can and relate.
"With gentle hands and the heart of a fighter, I am a survivor!" - Reba McEntire