Dude you really need to talk to her. Nonverbal queues usually tell more truth than verbal ones. She needs to be able to communicate why she’s crying. I’d hold off on sex until you can get to the bottom of it together. Trauma responses after sex are an indicator that something is seriously wrong. Make her feel safe about communicating. Please. If that doesn’t work, get professional help.
talk to her about it outside of a sexual context. explain that you know she keeps telling you she’s ok but you’re worried because she cries after every time. ask her if she could explain what’s going through her head when that happens. then ask if there’s anything you can do to make her feel better/help her/support her in the future if/when it happens
And you’re totally right for that. I think you should ask her about it but not right after you have sex. It might be easier for her to talk about that way. Tell her it makes you feel concerned for her and that it makes you feel like you did something wrong to her but focus a lot more on your worries for her than yourself