poor DH got blamed! This happened almost a year ago. I put a tampon in at night and forgot that it was there. When we had sex, the strings got pushed up inside of me. The next morning, I put a second tampon in and didn't realize it. Then, I removed that one. My period stopped.
For the next few days, I showered and had sex as normal, but I kept noticing an extremely foul odor. I kept blaming DH and really thought that he was pumping out something that smelled. I took multiple baths in one day and then ended up brain storming on the toilet. I remembered back to when we were younger and I ended up forgetting that a contraceptive sponge was inside of me. That was the only time I had ever smelled anything like this.
Sure enough, I shove my finger up there and the original tampon is still in. I tried desperately to get it out. When I couldn't, I begged DH to remove it. It took a few minutes and me spread eagle on the bed, but he loved me enough to get it out. It smelled even worse once it was out. Right now, I'm pregnant and my DH jokes when we have sex, "At least I know there isn't a tampon in there".