Brief Answer:
Air swallowing can be the reason.
Detailed Answer:
Hello!
Thank you for the query.
Excessive belching is called
aerophagia. Due to air swallowing, you get this symptom. Air swallowing can be caused by chewing gum, smoking, eating too fast, loose dentures, drinking carbonated drinks.
In rare cases belching can be a sign of some stomach,
esophagus or other abdominal organs issues.
I suggest you to try to eliminate mentioned factors first. If this wont help, you should consult your doctor and have some diagnostics. Abdominal
ultrasound and gastroscopy should be done.
for
constipation i would advise you following guidelines
have plenty of dietary fibers in diet like whole grains, fresh fruits like papaya and citrus fruits
have plenty of fluids 3 to 4 liters a day
regular bowel habits at least twice daily, even if you are not felling to defecate just visit the restroom
you can do
abdominal exercise by moving the belly in and out slowly
Hope this will help. Feel free to ask further questions.
Regards.