Sorry your mate has ohss
I had it severe and in hospital on a drip for nearly 3 weeks the best advice i can give is
1 ) Rest as ovaries so big so dont want to strain them
2) Drink water but dont overdo it as your body stores it
3) High Protein Diet - This worked wonders for me lots of yogurt, chicken etc
4 ) Plenty of fruit for constipation
Hope this helps, only from experience