I had the same problem with my 17 year old dog when I was in college and it's just something that happens to dogs in the last years. The vet will be able to help you by doing tests and determining if it's a bladder infection or just old age. Maybe some old towels for the doggie to sleep on will keep your bed dry. It must be bothering her to go around all day with wet legs and smelling like urine. She probably feels shame because she thinks she's a bad dog for messing in the house. She is not doing on purpose to make you angry. Love your doggie while she is here.