Its easy to over think things when you get injured; which sounds like your issue here. It's good to be cautious when you get injured but unless you have a physical therapist at hand whenever you need one it's better to just have a "shit, I'm hurt, better not do what I was doing until it feels better" than "Maybe it was x, y, x, the weather that day, the stars weren't aligned." This has been my experience in the past with injuries and when you start to over think things it tends to leak into your training etc when it doesn't need to.
Again, this is just my experience and it might be different for you. As for the hip thing, I've had something similar to it in the past. I never really found out what it was so I can't answer your question in that aspect; I think it may be that one of my hip flexors is tighter than the other, but there's no real way of knowing if it's the same deal for you. Just my two cents Man. Hope I helped somewhat.