Thanks for you query.
I read your query and I understand your concerns.
Following is my reply:
1) If you are suspecting pregnancy please get serum beta hCG
which will detect pregnancy at the earliest.
2) If not pregnant it might be just tension associated with thought of being pregnant or gastritis
3) Remember to use contraception
I hope I answered your query. I will be available for any follow up query you have.
Dr. Mahesh Koregol
IVF & Infertility