What Causes Burning Sensation In Vagina?

Hi! So my gf had an accident while she was sleeping. There was a man standing next to her while she was sleeping and he made touch his penis with her hand. She doesnt remember much but when she woke up, there was a slight pain/burning sensation near her vagina. But we are still confused if that person had sex with her or not ? Or just he played with her pussy area? Reply asap.