First of all let me tell you that you should not use any medicines without your doctor's advice. Secondly, Ativan ie. Lorazepam has the potential to make you get addicted to it. You can become a nervous wreck if you use Lorazepam (or similar ones) indiscriminately and for long time. Regular usage will tend to make you an addict. Therefore when doctors prescribe such drugs, they do so for a short while and then ask the patient to stop. Unfortunately many patients continue to take the drug without a doctor's prescription and get into trouble.
Regarding the question of combining Fluconazole and Lorazepam, you must leave it to your doctor to decide. But on principle, it is best to avoid multiple drugs while you are on a course of Fluconazole