I have a 4yr BO that is moving around very slowly, eats very little. She acts like she wants to eat, will pick a bit and walk away. She is extremely thin. I recently felt her croup and it was very squishy and when I tipped her forward brown liquid poured out. Today as she leaned forward to eat, brown liquid came out again. I know I'm losing her, due to her weight but I would appreciate any advice that could help. She is the sweetest little girl, a lap sitter.