For me, there was a lot going on during a therapy session that I wasn't comfortable yet recognizing and processing immediately, while I was in the session. So, when I'd leave I'd have lots of the symptoms you describe. It wasn't until I learned to contain all of the upsetting session happenings in the session and discuss them there, as they happened, that things got "quieter" for me afterwards. It takes awhile to get the two together so one is processing what's happening as it is happening and can immediately tell one's therapist, "What you said (and then paraphrase) makes me feel good" or "wait a minute, that makes me angry/that's not right/that makes me anxious," etc.