Check your attachment is right JIC she is swallowing air with her feed. If she doesn't burp it up it's gotta come out the other end.
Caleb tends to slurp a lot on his fingers and I think that is how he swallows a bit of air too.
Baby massage is great for the tummy. Same with nappy off time. It gets things moving so have a cloth nappy or an old towel under her!