Stomach Extension - causes

Is there a link between using a daily steroid topical cream for skin disease (psoriasis) and certain foods i.e. dairy products (milk) which would cause my stomach to extend so drastically that it is impossible to bend .. I am also suffering from increased muscle aches and pains.     I look 9 months pregnant.  The rest of my body is its usual average size.

This has happened off and on for many years... It does not appear to be "stomach bloating" as there in no signs of increased gas - but rather a swelling of the stomach.  It does reduce slightly in size overnight - but only weeks of dieting seem to reduce the extension once it has become a problem.  

The stomach swelling comes on gradually over a week or so and remains until I go on an extremely limiting diet - i.e. no salt, sugar, dairy products, fats,  breads or red meat.       When I return to eating normally.. my stomach problem eventually returns.

Is it usually food intolerance that causes extension of the stomach? or can it be triggered by certain steroid ointments? I was given a different steroid ointment to try a few days  ago which seems to have triggered this latest episode. Note:  I do have open sores that I have applied the cream to which I am concerned may have caused the steroids to enter my blood stream.   I do know that steroids taken internally for a prior eye virus caused extreme weight gain and extreme stomach extension - that is why I am asking this question.  

I have had recent blood work done and I am in very good health. (normal sugar levels etc.)  I have suffered from
psoriasis for 19 years and usually apply Dovonex twice a day.  My psoriasis has flared up very badly along with my stomach problem and so I am wondering if the two are related.  

Is there anything I can do or take to reduce or prevent the stomach extension. Thank you.

[KjFlicka]

One thing you said... when you limit your salt, etc., the bloating seems to go down... makes me think of "ascites" which is fluid retention in the abdomen and is known for making people look totally pregnant. Usually patients with ascites have to go on a very limited sodium diet to reduce the fluid. Just one thing to google and hopefully rule out.  Good luck!