Someone please help, what are the signs of a cat eating a poisoned mice ?

I have a 1 year old male cat that has always been very healthy, happy, playful & that i know of no bad health conditions. But lately he has been acting very strange. He usually meows all day, seeks for attention, eats well & is a very affectionate loving cat. But lately he has been vomiting orange, loss of appetite, so weak he does not have control over his own body & the inside of both his ears look like their full of blood. A few hours ago i went to the emergency animal truck which is for low income clients & after giving my cat a few test's they explained they still cannot determine what my cat has swallowed. I am assuming my cat must have ate a poisoned mice. Can someone please help me & tell me what i can give him for now. Since veterinarian is very expensive i feel really help-less. Its very painful to see him do nothing but hide and not being able to walk. Knowing he has not even been able to use his litter worry's me much more.