Oh no poor Bella, I've had a few dogs over the years with epilepsy(one I kept as she was too badly affected, others were adopted), I'd suggest keeping a diary to start with, note down what day/time they occurred and how long it went on for. That way you will get an idea of how bad things are. Sometimes dogs can have a fit or two and it never repeats, no idea why, but it happens.
I've found that if a dog has a seizure only every 6 months or so, it's best not to medicate, once it gets to once a month, or once a week especially, meds are the way to go. Then you have to find the right balance as the meds can make them very groggy.
There are a couple of commonly used meds (the names of which escape me atm of course!), the idea is to reduce the amount to as little as possible without break through seizures. It's a fine line, and sadly I've found that as dogs get older quite often the dosage has to be increased over time.
My little maltese girl was a severe epileptic, if I went out I would leave her in the bathroom (covered in newspaper) where there was nothing she could hurt herself on if she had a fit, and also where the other dogs couldn't get to her if she did - otherwise they would have a go at her (pack mentality). I'd know if she'd fitted while I was out because the newspaper would be all messed up and crumpled. Sadly her fitting became uncontrollable and I had to make the hard decision.
It's watch and wait time for Bella at this stage, fingers crossed it won't happen again.