Wiktionary
swell up
vb. (context idiomatic English) To become swollen
WordNet
Usage examples of "swell up".
Bingo's feeling of uneasiness began to swell up into a touch of panic.
He used both hands, looking for the inner lacings, and she arched her back helpfully, which made her breasts swell up into sight just below his chin.
Old Junior started to swell up right away, and Varia began to purr.
We should put it in shallow water, and let the wood swell up a bit and see how much water it ships.
The mere act of observing Kentucky from afar made him so angry, he wanted to swell up like a bullfrog.
He heard the singing swell up in chorus and he could make out the features of those in the front ranks.