HI thanks for your question.
Your's are two pregnancy
tests are negative but your having symptoms suggestive of pregnancy.
Pregnancy test usually comes positive after 10 days after missed period .
Repeat pregnancy test after 10 days of missed period,if it still comes negative.then surely your not pregnant
The other cause of your symptoms could be gastritis
(inflammation of stomach).Gastritis could be to increased acid production secondary to bacterail infection by H Pylori.spicy food and drugs.
I would suggest you to consult a physician who will evaulvate you for cause of these symptoms.
Hope this answers your question.