missing narcs

I went to work yesterday and did my shift change, the narc count was right, nothing seemed to be missing. Throughout the day one of our residents was needing her pain pill, so I went to the narc box and didn't find her med card, I looked through the entire med cart and couldn't find her pills. We have a signout sheet for narcs so I went to the folder to check and see if the narcs were being reordered, I found no signout sheet. So the next thing I did was checked the pharmacy slips, saw the meds were delivered the previous day, and that they were signed off by the RN. So again I went through my entire med cart and nothing. I asked the other RN if she could check her med cart in case the narcs were accidentally placed in hers, she says no. So I'm freaking out, I don't know where they could have put her meds. We call the DON, and ask if she knows anything about her narcs, DON says she has some meds and she'll go through them and see if she has them. No! The DON doesn't have them. So I search my med cart again, the DON looks through it, the RN looks through it, and NOTHING! 60 pills are missing. They call the RN who signed off for the narcs, she says yes they were received and she placed them in the narc box and placed the sign off sheet in the narc folder. That RN did her shift change and the Nurse who took over verifies that the narcs were in the lock box. So now they call the nurse who did shift change with me that morning, that nurse says no, I don't remember seeing any meds for that resident. So my DON tells me that I need to get done with my med pass, and go to the hospital and get a drug test. I show up and one of the other nurses is there as well, we talk for a few and she says that the meds were there when she left at 11pm. I told her I did not see any narcs for that resident that morning at 7A. I don't know what to believe, either someone left there med cart unlocked and unattended and some one else took the meds, or they were placed else where, or even worse one of the nurses took them. So now I'm stressing out, cause I don't know what's going to happen. I told my DON the narcs were not there this morning, I didn't see any narcs for that resident. I was off work for 5 days, normally I work a different side and hallway. So I'm not famililar with these residents, plus this resident had been re admitted after being sent to the hospital for a few days, when she was re admitted to the facility she had orders for this narc. How am I suppose to know what she is on?? I wasn't told during report that she was even in the hospital. I worked hard to get done with school and I plan on going back to school and hopefully becoming a nurse practitioner. I'm not being blamed for the missing narcs, my DON believed me, but I'm afraid of losing my job. Plus my hubby is stressing me out, by constantly saying what if you get fired for something you didn't do, and you need to find a different job. *sigh* he's not helping any by adding stress to this situation...