I'm sorry for your loss. She may have suffered internal injuries which can be common in these cases. That may have been why she wouldn't eat and drink.
Tylan 50 is used for the treatment of respiratory diseases, and some bacterial intestinal diseases. Vets will often prescribe clavamox or Baytril for wounds. Tylan is broad spectrum (treats gram positive and negative organisms) so it may help. Is she alert or in shock? I have had chickens...
The aspirin could cause bleeding, so I would probably not use it again. Chickens can do pretty well after deep wounds with good care, and preventing infection, along with good nutrition. Wounds should be cleaned with betadine, hibiclens and water, or dish soap and water, then patted dry. Stop...