While the submission and humiliation factor in an act such as this can be pretty intense, it is most emphatically NOT SAFE!!!!! While the question seems like you are looking for a bit of agreement even to the point of asking me to agree, it is not just me agreeing to make you feel better. It is unsafe, period, and your instinct on this is absolutely correct. There are bacteria in the colon that should NEVER EVER be ingested or introduced into other parts of the body. Even though these bacteria are in your body, they belong where they are. Here are a couple of my personal experiences to learn from:

When I first started working, I was with a customer who wanted to slide his finger into my ass. OK, he paid good money for it, so I let him. Before I could stop him, though, he slid the same finger into my vagina. Angrily, I explained to him what he had just done to me, though he did not believe me because it was bacteria from my body so it should be OK. What ensued after that was one of the worst infections I ever had, and I was out of work for over a month because of it.

About 2 years ago, I was with a great guy, and he loved playing with butt plugs with me. He pulled one out, and my guess is that there was some bacteria that got onto his hands. He then played with my clit for quite a while. The bacteria got into my urethra, and then into my kidneys, and almost killed me. I was sick for 4 months with a VERY serious kidney infection.

In my articles on this site, I warn about the use of things like Anal Lube because it can numb the rectal walls, which can be torn very easily. While slight tearing is not uncommon in bodily functions (lay off the cheese!), it can be downright dangerous if it is a lot. There have been many cases of gay men dying from the infection caused by bacteria normally present in the rectum getting into other parts of the body.

I am not a doctor, though I have experienced first hand some of the dangers that this bacteria can cause. Don’t just take my word for it, check with a doctor! If a doctor does not tell you that this activity is downright dangerous, he should have his license yanked, and fast. If your master truly cares about you, he will help you to do a bit more research into this practice and he’ll never make you do it again. If YOU care about you, you’ll say your safeword if it is ever expected of you again. This is not safe or sane, and it sounds as though it may not have been very consensual on your part, though only you can judge your relationship. I'm not slamming your master here, but if I were you, I would definitely ask a doctor, together. Hopefully, he loves you enough to not ever go there again.