I'm sorry she's not getting better.
You may be dealing with a virus or fungal infection if the antibiotics didn't help.
As for contacting a poultry expert, you can try contacting your local Agricultural Extension office to see if they can refer you to someone. Contact your own vet and ask...
Follow the instructions on the package of Tylosin powder that you purchased from Jedds.
Tylosin may taste a bit bitter, if you wish you could sweeten it with a little juice.
Your hen *should* drink the medicated water as normal - meaning she should consume what she normally drinks, this will...