Has Anyone else been experiencing constant nausea. All Day Everyday.?

I have had a constant feel of nausea for 4 months now. I have never been sick but have felt close on several occasions. I am a 16 year old male. I have been to the doctor loads of times and have had: Ultrasound, blood tests and a breath test so far. These all proved negative.

The nausea is quite bad and lasts all through the day. It is relieved for a short while when eating but comes back often worse afterwards. I have been given Lansaprozole, buccastem and motilioum by the doctor which help a little but do not cure it.

Has anyone here got a similar problem or no someone who has. Any treatments you can recommend. I will give 10 points to a helpful answer.