my boxer began dragging her back left foot and has gotten worse like she cant pick it up, then started pooping as she walked and now has no control over when that will happen. she is still very happy and likes to run and play although quite wobbly with her back legs. she sometimes seems like she doesn't feel well. what is going on with her, stroke? spine injury? cancer mass? I don't want her to suffer, but if she can have some quality of life left would like to help her