Crying after sex

I have this curious phenomenon that's begun to happen to me more and more as I've gotten older (started when I was 17 small handful of times during a relationship I was in,  now 23 and two relationships later it's started again. I'm single and sexually active with one person and after having sex I often feel the urge to cry. What's up with this? It's embarrassing and weird. While I have been sexually assaulted when I was younger I don't feel any after effects of it on a regular basis. I do however struggle with depression but it's been better lately. Recently, the crying took such a turn that it became a full on panic attack. Advice?