Constipation since 2 days ago! help!?

okay this may sound weird but its killing me! I have this thing that when i eat greasy foods/junk food, whole milk, chocolate, high sugar foods, meat, fruit, i tend to get constipation! and i tend to just burp out everything i keep burping and burping all i burp out is air ofcourse but with the flavor of the foods i ate. The only times i don’t get this is by eating veggies, whole wheat bread, and white bread/pasta. that is it! i hate it because i can’t eat anymore pizza, cookies all those goodies especially when i am a teenager!! grr anyways i get constipated, and if i drink water i tend to burp way more! i do get physical activity and pretty much eat healthy! so what is good for when you are constipated? and does anyone know what is wrong with me?? I had this burping problem that has worsen for about 3 years already, and constipation problem since birth!
what happens if its stuck there?
i did use laxatives like 2 times! prune natural ones