Go to the drug store and get swimmer's eardrops. They dry out the water in the ear canal.
Now, I want to say that what I really think is that she has swimmer's ear. And that needs a doctor's attention. Swimmer's ear is VERY painful. And it can travel into the middle ear.
The doctor can give you prescription eardrops, as well as antibiotics, if needed. Meanwhile, you can stave off swimmer's ear by putting the over-the-counter drops I mentioned in the first sentence after she comes home from each practice or swimming trip.