Advice pls???

So me and my boyfriend haven't been together for very long, we've had sex 3 times now, the first two times wasn't that good because of rushing, the third time was pretty amazing, although im getting frustrated at the fact each time the aftermath for me is not good, the day after I wake up to a swollen vagina followed by thrush. How can I prevent this from happening again? I'm not sure whether it's from not getting turned on enough or it's because the sex is too rough too quickly or it's from him sticking his fingers in straight away? Advice pls?