Serious question

So this doesn’t happen all the time but from time to time after we finish having sex she’ll get extremely nauseous and she’s even thrown up before she has pcos and I’m a little over 6” so not massive to cause problems like that but I do cum in her as we’re trying to get pregnant does anyone know what could possibly cause those symptoms at first it made me feel horrible but I’ve gotten used to it but still makes me worry about her