Your HPV test can be done at the same time as a Pap smear. Here's information about the test from the Centers for Disease Control and from the National Cancer Institute. The two tests -- HPV and Pap -- are commonly both done these days as part of a regular cervical cancer screening; you can double-check with your GYN to make sure the HPV test is being done.

As for the swish test -- that only indicates whether there is something in the area that got swished. Depending on gargling technique, the test might not reach to the BOT area, so even if there is HPV at the BOT, it may not get identified. Here's a thread about the limitations of the swish test.

And like the swish test, the gynecological HPV test is a snapshot of the moment it was taken. If your test comes back negative for HPV, that doesn't necessarily mean that your husband's tumor wasn't caused by the virus, which can lurk unseen for years. You may have been exposed at some point and then, like most people, simply cleared the virus on your own.