Now I'm worried about you! You might feel used to puking and feeling crappy at 25 weeks but don't try to tough this one out. I came down with stomach flu shortly after my morning sickness started to subside and I wasn't sure if an entire day vomiting every 30 mins was flu or ms but when my husband called after hours they told him I needed to come in immediately for fluids. Those first ice chips were like heaven & I felt incredible the second day. I could eat again and wished I had called sooner. Let us know how you're feeling later. I hope you're ok.
Push the fluids and call OB if you can't keep fluids down at all. Dehydration is dangerous to you both. If you're puking every few hrs for 2 days you should call right away. Call answering service if needed. They may get you on IV to help, check baby's vitals, etc. Never be afraid to call & discuss. 2 days without any fluid is a big deal, especially at 25 wks!
Also, you must get fluids. Effects of dehydration can occur very quickly and after 2 days you may become symptomatic. Don't ignore your lack of fluid intake.
If you develop severe hypermesis, you may need TPN nutrition which is IV feeding until you are able to "hold down" intake.
Well, you obviously need a proper diet but babies are like parasites. They will take what they need from you even if you lose weight but the best advise is eat a balanced diet and stay hydrated.