From my experience, Prednisone is notorious for packing on the weight (especially water weight)...I feel like a blow-fish half the time (smile).
I've always been told to watch salt, as lupus can affect kidney's (which mine is)....salt is out for me. I know it's hard getting used to; but once I got used to it and noticed that the pudgy face look was going away, I was willing to make the trade.
I'm sure Suze will be by to share her treasures of information with you as well as others.
I hope you and your son are doing well. Keep us posted and it's so nice to see you still posting. You're such a blessing to us all.
"I believe that friends are quiet angels who lift us to our feet when our wings have trouble remembering how to fly." - unknown