What's wrong with my beagle?!?

i have a 3 year old beagle and she is completely crate trained.whenever she needs to go outside to do her business, she rings the bell attached to the doorknob but today she didn't. All of a sudden she peed on her bed then ran away scared and peed next to our family room couch. i pushed her outside but she immediately peed on the concrete when she got out. Then she started walking down the steps but she was shivering and the way she stepped was like a robot. at the bottom of the stairs she sat down and she was shaking all over,drooling, and her eyes became unfocused. I tried to get her to stand up and go to the grass but once she stood up she started swaying and it looked like her thighs were flexing and unflexing really fast. she finally got to the grass and she lied down and drooled uncontrollably. 5 minutes later she got up really slow and started walking around like nothing happened!! She seems fine now but she acts nervous around me. This has happened to her before after she went jogging but she wasn't shaking or peeing uncontrollably. Did she have a seizure or something? what should i do?