Is there a way to reduce pred's water retention?

Sorry, there was a mistake in the title. I meant prednisolone.
Hi,
I started this month my second year of taking pred. I'm tapering it and I reached 7.5mg and will take it until methotrexate kicks in (only had 4 injections up till now). Symptoms haven't become better. Pain has become tolerable but D is still horrible. Today, I have extreme fatigue and don't know how to combat it. I'm quite sure that my doc will increase my pred dose again and I'm afraid of gaining more weight. I gained 10 kilos in 10 months. But the last couple of months, I was on a vacation, did not move a lot and suffered from severe low blood pressure that caused a lot of fainting and necessitated increasing my salt intake. This in turn, caused my water retention to increase and I've put on a lot of weight. I'm really depressed and don't want to gain any further weight. By the way, I do not exercise and the only thing I can do is walk because of my GERD.
My question is: Is this water retention reversible? I decreased my food intake, drink a lot of water and try to avoid salt as much as possible. I read that increasing the potassium intake can reduce water retention. The last couple of days, I ate bananas but my proctitis deteriorated and D has become horrible and I don't know whether there is a connection or not.
Is there a way to reduce water retention without decreasing pred or is it connected to it? Hence, I'll be still gaining weight for a long time ahead.
Your replies are highly appreciated.

Ivy6,

Thank you very much. What you are saying seems to be true, especially that the diarrhea has become horrible and Lomotil does not make any effect now.

I"ll abide by whatever my doc says.

Hugs :)