enlarged spleen,liver,gall bladder and suppressed blood cell production

[tracemace]

My 9 month small breed dog (dachund X) has recently started spiking a very high fever and was very lethargic. I took her to the vet who put her on an antibiotic, and gave her an injection to reduce the fever.  She seemed so much better after the fever came down.  However, when the fever was still spiking two days later, with the course of antibiotics completed I took her back to the vet.  He said that she seemed to have a very tender abdomen and that he would like to keep her for the day to run some test and do an ultra sound.  When I went to fetch her later that afternoon, they would not release her to me, saying that her blood platelet level was extremely low.  The following organs were enlarged: liver; gall bladder (with thickened wall) and speen with the spleen showing some irregularities.  She also has a very low white and red blood count showing that the bone marrow is not functioning correctly. Other than that she is playful (when her fever is down) and has a healthy appetite.
1.  What are the chances that the dog is being poisoned by my domestic worker? (just a suspicion)
2.  What could be the cause of all of the above?