If you're currently using the mirena as contraception, I'd use some sort of back-up method until you can get it checked out. When you say the strings are "sticking out," do you mean sticking out of your vagina? Or that for the first time, you can feel them sticking out of your cervix? If you're relatively aware of your cervix position as your cycle changes, and your strings are significantly (2-3 inches) longer than they normally are, even if you can't feel the plastic tip of the IUD, it's potentially a sign of a partial expulsion. If you are expelling, proper medical care involves having a HCP remove the device.