Getting head

My boyfriend used to LOVE giving me head ALL the time. He never really cared at all, it used to be his guilty pleasure and loved pleasing me and making me cum everytime because it took less effort instead of having sex. One day he suddenly stopped giving so much effort and dreaded doing it. TMI but I asked him if I started to stink?? And I think he was lying, or had a different taste? We've NEVER had this problem before for months. I don't know what happened.