Hello Heather welcome to The Garden
Nice to have you here.
I don't think you were well advised to give her corn. Corn is not easily digested and tends to firm up droppings. What makes you think it is constipation? If it is the fact that she is not passing much poo it could be a stoppage in the crop. Check her crop in the morning. If it feels hard and you can feel the food in there the bird is crop bound. This is often caused by the bird eating long stringy grass that forms a ball in the gizzard.
Treatment for Crop Bound
The earlier that you discover the problem the easier it will be to solve. First put the bird in a pen that will not allow him access to any food including grass and dirt . Take some ordinary plain
( unflavored ) yogurt, the natural kind, and mix it with some cool water to make it syringeable and squirt it down his throat several times a day . You might want to mix a small amount of Vit & Elec with it as well . Massage the crop vigorously to mix the contents with the yogurt . Keep doing this until he starts to pass the feed. He should be cleaned out within 24 hours . Next take a hard boiled egg and mix the yogurt with it and feed it to him for the next 24 hours. When he is passing this feed without any problem bring him back on a mixture of the feed that you normally feed mixed with the hard boiled egg and the yogurt until over a few days he is eating and passing the feed without difficulty. Then put him on his regular feed. During this time the bird must have plenty of fresh water with Vit&Elec in it as well.
Stay away from using bread,milk,and oils as they are hard to digest at this time when the digestive system is under such stress.
If the problem is constipation feed her a little olive oil through a syringe.Also give her some greens well shredded. Keep her isolated and warm.
Come back if there is anything else and let us know how things progress.
We are all visitors to this time, this place. We are all just passing through. Our purpose here is to observe, to learn, to grow, to love...and then we return home.
Australian aboriginal proverb.