What exactly is nausea?

What causes this random nausea?

• So almost two months ago i had food poisoning, at least i think it was food poisoning well i woke up at like 12 in the morning and i didn't have dinner that night and for about 2 hours i felt really bad nausea and i felt like i was going to throw up but instead i kept retching and nothing came out but i guess that's because i didn't have any dinner. So from 12 am to 5 am i felt nausea and kept retching and it happened 3 times and then i had to eat something for breakfast because i was hungry but still felt very bad nausea. After i ate at 9:00am i felt like i had to go urinate so i went to the bathroom and as soon as i got there i threw up. I threw up the food i had the day before for lunch and it was like sort of undigested. My parents said that it must've been food poisoning but i don't get it because we all ate the same lunch and i was the only one who got sick. But, that wasn't the bad part, after throwing up the nausea lasted for more than 2 weeks, every single day i would feel it for more than 6 hours straight but i never vomited or had diarrhea ever again. We went to the doctor and he said that i should get an ultrasound done, and also blood tests, and tests for my liver and gall bladder to find the cause of the nausea, and even stool samples but all of these came back normal there was nothing wrong with my liver, gall bladder or blood even on the ultrasound everything was fine so I was getting really concerned. It was getting in the way of everything i was doing, i'm 15 by the way and i had to miss alot of school days because of it.So after 2 weeks, I started to feel better but then at times i would still feel nauseous and then it was spring holidays and many weird things kept happening to my stomach ! like i would feel bloated with the nausea for i guess a week and then finally it stopped i thought i was cured but again a week later i started feeling the same type of nausea but this time there was like a lump in my throat and i kept swallowing to push it down so i went to the doctor and i asked him if it could be acid reflux and he said it could be but we weren't sure because i had no burning sensation in my throat just the lump and nausea. He put me on nausea/vomiting relief medicine and antacids but still after taking these medicines nothing changed. Once again i started to feel better and again it came back, but this time no lump feeling just like i actually felt like throwing up. The nauseous feeling i had before was something i could control and withstand but this time it was so hard to swallow i tried so hard to not throw up even though i knew i wouldn't throw up because it was happeneing for 2 days so if i had to throw up i would by now but i never did, now it's disturbing my sleep everytime i layed down and closed up eyes i would suddenly wake up with a jerk because i had to swallow to keep it down and it;s really uncomfortable :( last night this all started and now it's 5 in the morning and i've been awake since 1am :( Tried eating crackers as i couldn't eat well at night and i also tried eating an apple but still the feeling won't go away. The doctor said that I should have an endoscopy done and i'm going to do that in 2 more days but i'm really confused because i have never had any trouble with my stomach before, I always used to eat so well, never had food poisoning for 3 years now until 2 months ago and this all started then. I really need help :( does anyone know what could be wrong ?? i'm trying to avoid the endoscopy :( I'm so sorry that this question is so long but i had to explain everything that happened these two months :( Please can any help ?? Answers would be appreciated ! Thank You !

• Answer:

  I don't know. I've had it from time to time. Get your ears checked, also, maybe.