I had a gastric sleeve approximately 7 weeks ago but have severe nausea!

I try to follow the diet rigidly but as a result of the nausea I struggle to eat anything other than potato,even sipping drink is hard. I try to eat meat & veg but it just doesn't go down well so it's just varying types of potato. Understandably I'm not really loosing much weight which is frustrating to say the least. I have tried going back to blended food but it doesn't seem to help. On a plus the diarrhoea stopped at week 5!