Steve, glad to hear it worked for you. I have similar problems at times and the exact same effect. 5-htp for Depression is equivalent for me of a theanine for anxiety. It's good for long term stability but also for "emergency".
Good point on SSRI and 5-htp but if you're that low, it's probably not a terrible thing (but I'm not a doctor).
Another benefit is that if 5-htp has that much effect then you likely have low serotonin. So boosting your St John's Wort or SSRI that you're taking will help. It did for me.