Yup, I've had this happen a couple of times, and they've both happened when I haven't gotten to explore everything in that 50 minutes. And it's all of the feelings of guilt, yearning, shame, who-knows-what rolled into one. It's like something gets off balance in my head and emotions and it's one of the deepest and rawest emotional pains I've ever experienced. Last time I wanted to immediately burst right back into my T's office as soon as the door shut and didn't stop crying/being on the verge of tears for two days. I'm not used to needy feelings like that, so it was all sorts of confusing.

It's not a good feeling, but both times they eventually passed for me. I emailed my T during those times too--though I never really went into full depth into what happened, just that I was messed up emotionally--and it helped a lot. Maybe that could help you?