I've never had an issue from a checkup or cleaning. I did experience spread when I had a root canal and bridge, then again on the other side with a root canal. (I don't know if it was something about the bridge or the root canal I had on the front tooth of the bridge that caused it, don't frankly care at this point.) I've had extensive work done after other medical issues left me with a mess to fix. Fortunately I'm done now. (or as done as I'm ever getting because I won't let someone bridge between two perfectly healthy teeth and there ain't no way someone is drilling a hole in my bones on purpose) I still get my regular checkups, but because I've already experienced spread into my face I am planning on taking a pain pill before my next checkup. Not because they've been painful in the past, but because the idea of someone touching my face and in my mouth is enough to make me cringe now.

Don't let fear stop you from getting a cleaning. Preventing the need for getting actual work done is the best thing you can do (imo, after my experiences) to keep there from being spread in the area. Just make sure you talk to the hygienist and the dentist before they touch you, explain the disease to them and the special care they must take not to cause physical harm while doing the cleaning. I'm not saying that it couldn't possibly cause spread, heck that can happen for any reason or no reason at all apparently. But better to make sure your teeth are in good health than to risk needing serious work done makes them need to drill or even worse, actually mess with your nerves on purpose as they have to in a root canal.