This article lists most of the drugs known have the potential to cause drug-induced Lupus.
/en.wikipedia.org/wiki/Drug-induced_lupus_erythematosus. Have you been taking one of them?
I caution you against self-diagnosis. A positive ANA doesn't necessary mean you have a disease, it's just an indicator telling the Dr to check you for symptoms of auto-immune diseases. And the nuclear pattern is most often seen in scleroderma patients, not Lupus.
Read our Lupus 101 thread on how to prepare for your first rheumy appointment. Take the Dr a list of your symptoms and when they occur, as well as a list of your medications and how long you have been on them. Let the Dr decide on which, if any, diagnosis fits. Avoid mentioning any particular diagnosis, it can cause the Dr to inadvertently fail to consider things that may be real possibilities.
Let us know how it goes!