Thanks for your question on Healthcare Magic.
I can understand your concern.
No need to worry for major heart or lung or abdominal pathology for your symptoms.
I don't think it is
costochondritis because costochondritis can not cause burning and pressure kind of pain.
I still feel that your symptoms are due to GERD (
gastroesophageal reflux disease).
Upper GI (gastrointestinal) scopy can be normal in GERD. So negative scopy can not rule out GERD.
Some lifestyle modifications are sufficient to treat GERD without taking
nexium.
So follow these steps for better symptomatic relief.
1. Avoid
stress and tension.
2. Avoid large meals, instead take frequent small meals.
3. Avoid hot and spicy food. Avoid junk food.
4. Quit
smoking and Alcohol if you have these habits.
5. Go for walking after meals.
6. Keep 2-3 pillows under head in bed to prevent reflux.
Don't worry, you will be alright with all these.
Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.