Its generally considered normal and not a cause for concern. It can occur when the blood takes longer to leave the uterus and partially oxidizes.

Toward the middle of the pregnancy, a smaller belly at 17 weeks might trouble you. If a belly is small, it can be because of the baby’s position, the way your body is holding the baby, or many other reasons. In the majority of cases, it's not a big deal when your health conditions are within normal limits. Continue to eat well and go to all of your pregnancy medical check-ins to ensure that you and your baby are healthy.

To prevent your period from starting, you should take the blue triphasil tablet from the pack. By taking this tablet, your body is prevented from releasing the egg, which can be the reason behind the delay of your period. The scenario becomes bright when you have a special event or a trip planned, and you don't want your period to come. Triphasil is safe to use for this purpose, but you should always follow the instructions and take the pills every day at the same time.

It's difficult to determine the exact cause without further info.. Stomach aches can have various causes which are unrelated factors like stress or dietary changes. If you're concerned about pregnancy then you may take a pregnancy test for confirmation.