Help get dodger diagnosed

Hi im alison and im asking everyone for the help to to get a diagnosis for my baby .so here is his story So back 4 months ago my 6 Yr old staffy lurcher was sick and very bad diarrhoea. SO we took him to the vets he had bloods and his liver Enzymes where that high the machine couldn't even read them. He was put on lots of meds and told me it was touch and go .We went back month later to repeat bloods and they where back to normal and he could come off all his meds .He seemed to be getting better.Fast forward to 4 weeks ago and we noticed he was circling more than normal and very hyper.we took him to the vets and they said they wanted to scan him and repeat some bloods which came back OK.They thought he had a shunt but bloods came back normal.He has lost alot of weigh in a short space of time and started to lean to the left. They said he may have a brain tumor or cancer on the brain due to his rapid weight lose and his circling and leaning .His on a course of steroids and got to go back in a week .But the only way to find out is an mri which is £1500.we have spent nearly £3000 on him already and not prepared to give up on him now .He is eating weeing pooing drink and doesn't show no signs of pain .He means the world to me and my daughter and we are heartbroken we are trying are best to get the money together.Thank you for taking the time to read .