Why do i burp so often?

for a long time now i have been burping way to often. and there not little burps either. if i dont have my mouth closed people up to 30 meters away can hear me. im currently at school and whenever i need get up the tairs(3 levels) i always burp. even just sitting in class i burp. after playing basketball i will burp. i dont know why this is and its not very attractive. i just want to know why this is happening and how i can stop it. i even did a burp while typing this. a small one tho