Unfortunately,
vomiting, lethargy and increased respiratory rate all have can have
multiple causes. Some can be serious and others not so serious. She might have eaten something that either disagreed with her or may be causing an
obstruction somewhere in her gastrointestinal tract. She could be sore from an unknown injury. She could have been exposed to or ingested a
toxin or irritant in her environment or this could be early signs of another condition or disease process. A complete physical exam by your veterinarian or at the nearest veterinary ER would be recommended if symptoms persist for more than 24 hours. Supportive care (IV or subcutaneous fluids, medication, etc.) may be administered until a diagnosis is reached.
Your vet can perform an exam, blood work and possibly x-rays to determine the cause of the illness and suggest an effective treatment plan.