Hi. I would say a couple of things here ... first, what is the food you give your dog each day - please include full details, including any treats. Second, seizures are truly petrifying for dogs. They always suffer an element of disorientation, even when you think they don't. Some dogs bounce back quickly and are so reassured to see you they just seem to carry on as normal, but actually, the pre-fit and post-fit event stays in their memory as an anxious and frightening experience. This low-level anxiety can give bowel problems, including constipation or diarrhoea. It should settle back to a normal routine - but if not, then it is useful to alter the diet slightly to accommodate the change and make things easier for them.
It is likely the seizures are genetic-based, considering the age of your dog, which means the seizures are likely to get worse over time and will certainly need treatment for the rest of her life. It could absolutely also be due to Valley fever, or the aftereffect of it which is known as Disseminated Valley fever. This is where the original infection has spread outside the lungs. If the cause was Valley Fever, you would remember your dog suffering severe hacking and coughing. Do you remember this happening? Very rarely, a dog with Valley Fever will not suffer a bout of coughing. There are two other potential possibilities to be aware of ... 1. Brain tumor; and 2. Toxaemia. Both can bring seizures. Has your vet considered these potential causes and investigated them?