I assume your bike is older style cup and cone BB, with the drive side cup unthreaded. Yes, there is a thin spanner wrench that is used. Believe the size is 36mm. If you can get the drive side crank arm off, then you can use Park Tool Model HCW-4. I believe you can find thin open box style wrench, but don't know who makes them. As an alternative you might be better off taking it to your LBS and have them tighten it. Yes you will pay labor but that will be offset by not having to buy a tool,

Karl