Amber, if your cat is between 5-10 mths, it is very common for the kitten to have bad breath as he/she is teething and growing. My vet, and 2 other online vets confirm this. I was worried too about Pixie's bad breath, which smelled extra fishy strong, and also had a big red bubble on her gum, so of course I ran her in to the vet, where he said her breath and the swelled gum (erupting tooth) was normal for a teething kitten. The gums cleared up by itself in 4 days, and I saw a little white tip. The breath is less stinky now.
Besides the breath, another indication of gingivitis is the border of red inflamed gum lining all around the teeth. The vet thought Mozart had this at 7 mths, but no bad breath. He was scheduled for a vet cleaning a couple mths later, but it cleared up by that time. In hindsight, because of his age, I think it was related to his teething. BUT if the cat is older, it's NEVER going to go away, it only gets worse, and you have to take them in for a cleaning.
Spica isn't, but if the cat is older than a year with extra stinky breath, then there are possible health problems already discussed in earlier replies. In your case, I got the feeling that you weren't sure how strong a cat's breath should be, and weren't used to it. It should not knock your socks off if she yawns a foot away from your face. But you're visiting the vet soon, so you can get pointers on what's too smelly, and it could take a while before you can brush Spica well. Pixie still is Ms. Squirmy, and it's been a month since I started.
OFF TOPIC: Alrighty, I got in here just to answer a bad breath question, but gotta say I agree with Sicy's observation. I've noticed the same thing. No need for any of the mods to reiterate your position after my reply; The Policy is posted above very clearly in several replies, and we got the message. Go to a vet. TCS is not liable. Better safe than sorry.
Other people's experiences or advice is what I want to get if I'm asking about a problem. Ending all replies with a "Go to the vet" disclaimer is fine. But it's completely unhelpful if the only advice in the post is "Go to a vet immediately", and it's equally applied across the board big or small, whether the cat is shedding a nail or going into seizures. That's all I'm going to say about that.
Amber, sorry to go OT on your thread, hope your visit to the vet turns out uneventful. Please let us know what they say.