my friend was diagnosed a few weeks ago. at first he was very open, telling only myself and another friend. he made us promise to not tell anyone else - which we obviously obeyed. however, since then he's become distant and has stopped sharing information about his doctor's visits. we want to help him, but we can't get him back and we're afraid that he's trying to deal with this on his own. we've tried everything short of holding him down ourselves... is this common and what can we possibly do without driving him away further?

You will need to be patient. Let him know that you are available any time he wants to speak with you. Let him know that you are concerned and welcome him to be open with you. Howeveer, as you noted, you cannot force him. For whatever reason, he prefers not to talk right now. It is his choice to keep his medical information private for now.