Why do I feel nauseous and vomit after eating?

You've had such a bad time with fever and diarrhea. Both could be the cause of your weakness later. The fever and the diarrhea ached your body thus, making you feel tired. You must hydrate yourself with water and soup. Light and easily digestible meals should be your priority. 

Your friend might be having a serious issue like internal bleeding. The bleeding from the bottom, stomach burning, and feeling sick could mean something is wrong inside her tummy. She needs urgent medical help to figure out what's happening and get the right treatment to stop the bleeding. 

You might have a condition called indigestion. Symptoms include weakness, a bitter taste in your mouth, and lack of energy even after eating a meal. Overeating is another factor that can make it worse. To get better, you should eat smaller meals, and non-spicy food, and not lie down right after eating. Avoiding late-night snacks can also be a nice decision since it will help you relieve symptoms.

Abdominal discomfort, nausea without vomiting, and we­akness afflict you presently. Pote­ntial causes include stomach infection or gastritis, an inflame­d stomach lining. Recommendations: consume bland, light me­als, hydrate adequately, re­st sufficiently. Persistent symptoms re­quire medical evaluation.

In their mouths and saliva, rats carry dangerous germs. If you eat food that happened to be gnawed on by a rat, you might develop symptoms such as stomachache, vomiting, or diarrhea. Ensure that you take plenty of water to keep yourself well-hydrated then look out for any serious signs like high fever. Just in case they occur, visit a doctor who will evaluate your condition further.