Well, actually, plenty of people don't like getting their pussy licked
all the time. Don't think that this means something is wrong or you are doing something incorrectly.
She could have a sensitive clit, or she might need to be in a specific mindset to enjoy oral sex. Try to take into consideration her mental and emotional state when she is telling you she doesn't like something. For many people, different aspects of sex are tied to very specific moods, and she may not be in the "mood" to be licked, but may be in the mood for pain, or penetrative sex, or whatever.
As for her interest in pain, asking her what feels like a "punishment" to her is a good place to start. It's not uncommon for people to view spanking as an act of punishment. Presenting to her alternatives such as biting, scratching, hair-pulling, or pinching might give her a better set of activities to choose from that don't feel like traditional punishments. Also, it could be the location or implement. For instance, spanking her ass with your bare hand may feel like a punishment, but smacking her boobs with a crop or flogger may not feel like a punishment.