I am sorry to hear that you are in this situation! Unfortunately, there are some conditions, many of them autoimmune or joint conditions, that do require taking steroids like prednisone for long periods of time.
It is true that prednisone (and all other steroid medications) can cause many side effects. Among these are the psychological side effects that you have read about online, which can include mood swings, depression
, and agitation. Fortunately, these effects are usually most pronounced when you are taking very high doses of steroids and they tend to be worse earlier on and diminish as the dose of steroids you are taking goes down and as your body becomes more accustomed to the medication.
Therefore, I think you will need to talk to your doctor
to figure out what kind of dose of prednisone we are talking about here and what the plan will be for tapering down the dose. Unfortunately, however, most of the conditions that require long courses of treatment with steroids like prednisone are quite serious and so I think the benefits of taking the medicine will likely far outweigh any potential side effects. However, only the doctor who knows your particular condition well will be able to answer this question definitively.