I assume for the fractured leg that you got painkillers?
Take a few of those, they will take the edge off and you won't be scared of calling. Call boss, explain situation, that you will return to work when your doctor says it is okay (since your job requires a lot of moving around). Or ask him if there is something less physical you can do, so you can return to work in a couple of days, do that stuff till leg is okay, then return to normal tasks.
Do this now. Or man up and skip the pks, but you got them anyway, and trust me the pks will make it easier.
edit: Why did you ever decide to text message him? I can understand being shy, but in this case you should've called this morning to let him know, he wouldn't be mad.
No matter how shy, there is always at least some things that you just have to do, comfortable about it or not. So if you absolutely could not call him, why not send an email last night? Not ideal but surely that would look better than a text message!!
So you need to fix this here, which you can do with a call, see my advice above.