I'd caution using made-up swear words...well...cautiously. When they work, great, wonderful, they're unobtrusive, but when they fail, they're a bit sad. (Anybody remember "tanj"?) You can get away with all manner of religious curses, but bad words are culturally ground in, and not so malleable.
For expletives, the old stand-bys for practically every human society are sex and excrement. No matter what your religion, those two are great favorites. (Blood works too.) So when he breaks his ankle, I'd suggest that perennial favorite, "OH ****! MY F*CKING ANKLE!" and even if you worship a goddess, you are still likely to recognize the less stellar qualities of dogs, so there's always "Son of a *****."
Be wary of particularly lengthy constructions. My Catholic grandmother liked "Saint Anthony!" as her profane standby, but in times of stress used "Jesus, Mary and Joseph!" and "Holy Mary, mother of God!" but she was a very specific sort of character--there's a lot more people who simply yell "F*CK!" and if everybody's curses go on for five lines, it starts to get stilted. Anne Bishop comes to mind--her great curse was "Something something, something else, and something something something something!" with the end result that all of these tormented sadomasochist characters reminded me irresistably of my Catholic grandmother whenever they were upset.
I think the thing is--stuff like "Sweet Jesus!" or "Saint Anthony!" are easily interchangeable. Mild curses based on the names of holy figures, you can do a fair bit with, because it's a completely understandable construction. We understand that people yell the name of a god when they're upset, we get that. So your characters can yell "Sweet Meredith!" or "Holy Bonejigger!" or whatever your gods are named, and it's comprehensible.
But when you get into stuff like "****!" where it's not a construction, it's just a bad word, something that our culture has agreed collectively is naughty--that's pretty hard to fake. There's no cultural weight behind it, so we're not shocked by the bad language, we just go "Okay..." It's not something where you can just change out the word for a synonym, either--if someone breaks their ankle and yells "FECES!" they're gonna get a lot of really strange looks.
So I guess what I'm saying is that you can easily come up with a curse with the impact of "Sweet Jesus!" or "Saint Anthony!" because they belong to a fairly weak category of religious curses, and they're easily interchangeable. But you'll have hell's own time trying to make up a word that's got the impact of "****."
Note: The censors really ate this post, huh? Insert a four-letter word for one's excrement or the verb to excrete in place of all the asterisks, and you've got it.