MDMA does mess with your anxiety for sure. I used to have big time social anxiety about a year ago, then it went away, then the anxiety came back from my abuse, but it's no longer social anxiety, I have no problems having laid back conversations with random people, it's just anxiety for no reason now, I feel like everyone/whole world is against me when I'm alone, it makes me antisocial, I need to force myself to go out, but once I'm out I'm like a normal person, super easy to talk to with/pretty cool. Now I take benzos (Klonopin/Xanax) to call me down between rolls and on comedowns.
But this anxiety getting worse thing comes from long time abuse. Next day you will most likely just have an afterglow or feel drained.