Mikeythrash

So my xj I was driving other day got stuck in 3rd at about 35 mph pulled over and I hardly had any trans fluid in it and engine light came on.put some in checked yesterday and there was hardly any again and it was brown.i am gonna check again today to see if it is still brown and why is it eating the trans fluid like it is? and how can I tell if someone changed the mileage on me or not from previous seller? I have a feeling it has way more miles then it says.