I have a 3 yr old English bully and she has always been in good health. Starting about week ago I noticed on about 4 different occasions now she will be sitting or lying down resting and her body starts to shake uncontrollably. The first few times were almost unoticeable but tonight she was shaking pretty good (reminds me of old person when their hands or heads shake) When I pet her it slows somewhat but then would get worse again when I stopped. I had her get up and walk - she had no problem- but her head still shook. It only lasts maybe 2-5 minutes at a time. Anyone have any idea what it might be or what is causing it?? Thanks!