I am sorry to hear that Jazzy is experiencing repeated seizures today.
There can be several reasons for seizures.
The most common is idiopathic epilepsy. That means that we don't know why but a circuit of sensitive neurons in the brain gets stuck repeatedly firing. Epilepsy begins happening most commonly in dogs 6 months to 6 years of age so she is really too old for this to be the cause of her seizures. We do believe that there is a genetic basis for dogs to have epilepsy as certain breeds are more commonly afflicted and siblings will often have them as well.
Other causes for seizures include viral, bacterial, parasitic or fungal infections, toxin exposure, metabolic diseases leading to waste products building up and affecting brain chemistry, very high or low blood sugar, or even granulomas or masses in the brain.
Most of the other disease processes that cause seizures cause other symptoms, those dogs are sick or abnormal other than during the seizure episode. In most cases with more "benign" seizures causes they recover pretty quickly, within 10 minutes or so and seem to have no residual effects other than being tired, hungry and thirsty.
Since she is not stopping, and is continuing to seizure every 5 minutes I am more concerned. I am concerned she has a serious disease process leading to this episode. I would think primarily along the lines of organ failure, for example diabetes, which can cause increased drinking too and seizures if unregulated, but other diseases like hyperadrenocorticism (over active adrenal gland hormone production usually caused by a pituitary gland tumor), or unfortunately a brain tumor are also possible. Lyme disease can cause seizures too, but I would have expected other symptoms before this (fever, lameness, joint swelling).
My primary concern is that the seizures are lingering, especially if she has no prior history of seizures. That increases the odds of her having permanent brain damage or going into a state called status epilepticus (one seizure after another with no break) which can lead to significant brain damage, and death. I highly recommend that she be seen by a veterinarian on an emergency basis today, or tomorrow if she suddenly stops and seems stable.
They will likely want to examine her, perform some testing of her nervous system reflexes and run blood tests and possibly keep her for several hours for observation, intravenous drugs to stop the seizure cycle, and intravenous fluids.
You are very limited on what you can do at home. All you can do is keep her warm and quiet, make sure she is on a padded surface so she cannot hurt herself, and have her seen by a veterinarian as soon as possible.
She may normally be a sweetheart but please be careful around her today. She may be afraid, and she likely isn't thinking clearly, and may snap unexpectedly.
Please let me know if you have any further questions.