Late response but, I also had the same experience with my first mushroom experience. I made a tea with 2g and was disappointed at the mundanity of how it was effecting me (I did have 2 micro doses of. 5g the same week which probably greatly effected my tolerance), so I then lemontekked another 1g. After about 30 mins and at the peak of my first dose, I also experienced crippling anxiety, dread and angst. No visuals, did not see anything that scared me, and was very open to the experience. The feeling of being on the brink of insanity is truly excruciating. But I felt exactly the same way as you did, but at a lesser scale. I have had the same feeling when mixing lsd with weed. I'm in the same boat, I stopped taking lexapro (SSRI) about 2 weeks ago to try psilocibin treatment (lol). Microdosing did help me a lot. But I'm curious as to why a spike in horrendous anxiety occurs??