Nausea and constipation. 😰

Annabel • "For this child I have prayed..." 🛐✝
I heard that it sometimes comes back in the 3rd trimester. I'm hoping to stay ahead of it but I've already fallen behind. 😩 
I'll be 30 weeks this week and the first 16 weeks I had hyperemesis. NOW for the past few days I've been nauseated again. I've only thrown up once so far.  I'm just trying not to....you know...because EW. I'm ALSO having trouble passing anything, which I know is leading to my nausea because I'm so backed up. I'm trying to drink as much water as I can to stay hydrated, because I have been dehydrated twice and in the hospital.  BUT I literally pee all the water I just drank out, 5 minutes after I drink it lol. And getting up every 5 minutes is quite the struggle. 
I haven't been hungry for like 4 days. BUT I've been eating anyway because I wanna feed the baby! But I definitely haven't been eating a lot. 😰 
So, I'm neither hungry, or full. I go to eat and I feel the same as I did before I ate....Neither full or hungry. What do you suggest I do? What are some good things to eat to get the nutrients I need without stuffing myself? 
Also, at night I'm having trouble sleeping because of RLS and having to constantly pee. Any tips to help RLS? And also, when should I stop drinking for the day to keep from being up all night? 
Thank you all! 😊