hi i had gone through your query and understand your concerns. i would come up with two most possibilities to fit your condition .these include
1.first possibility is,PREGNANCY;confirm with pregnancy kit test ( urine test )available in the market.
2.second possibility is,gas trouble (or APD ACID PEPSIC
DYSPEPSIA ).irregular dietary habits,modern lifestyles (drinking,
smoking,etc),EXCESSIVE USE OF PAIN KILLERS,ANTIBIOTICS,
STEROIDS for even minor complaints, CURRY,HURRY,,NIGHT WATCHING,SUPPRESSED STRONG EMOTIONS are the main causative factors.
I hope this is helpful for you, thank you