Eggbound Pekin duck

So our 10 month old Pekin hen appears to be eggbound. She has been laying for a few months and suddenly today I see her laying down in the middle of the lawn, away from the others, with her tail going up and down as though she is constipated or trying to pass something. I've seen her poop so I know it isn't constipation and I pulled out one less duck egg than usual the last two days. I have her in my bathroom right now with the temperature at 80 in a lukewarm bath and she seems to be swimming around happy. She has been getting layer feed and I do not have any additional calcium supplements I can give (unless some can be found at tractor supply?). What is my best course of action here? She does not seem to be in pain nor is she not eating (still snapping up any mealworms presented to her) but my husband and I both agree her behavior is not normal.

Thank you for the help!

This is how they acted when their egg bond, but I've never had this happen. You can buy oyster shell from tractor supply as a supplement.

Should have mentioned - they do have oyster shell available. What do I do now since she is egg bound?

I'm going to quote what Metzer Farms says to do.

'If a bird cannot lay an egg, she is considered Egg Bound. It can become a very serious condition. It can be due to an infection in her reproductive organs, a soft shelled or misshapen egg, nutritional problems or obesity. It is also more likely in young birds that have not laid before. But none of that matters when it occurs.
Catch the duck and lubricate the cloaca and egg (if it is exposed) with KY Jelly, being careful not to tear the lip of the cloaca, and then place her in a warm, moist environment. Try setting her in a pan or pool of warm water for an hour. If this does not help, try gently massaging the egg out, continuing to lubricate the cloaca.
The last resort, if the egg is exposed, is to put a small hole in the egg and remove all the contents with a syringe. Then you must break the shell and remove it. Be very careful as the edges of the shell are sharp and can cause lacerations in the oviduct. If you must perform this operation, then you should put your bird on antibiotics for a week after the operation.'

I can feed the egg when I put my fingers in her vent but it is behind a membrane. It doesn't seem to be in the place I would assume it should be.

I am feeling the full egg on the bottom left hand corner of her clocoa, not above. That does not seem to be good.

Try massaging it out and if that doesn't work you should probably take her to the vet.

Thank you! Have a call into the avian vet.

After treating her through the night with multiple baths, massages, TUMS in her food, calcium drops in her food, and lots of lubricant, she managed to pass the egg at 7:10 this morning and now seems to be doing well. Thank you for all of the help!

That's good to hear, and I'm sure she's relieved as well!