Does anyone here take L-Theanine?

I started taking it a couple of years ago. It was great for the first couple of weeks. One 100 mg capsule was enough to make me feel calm. But then it started making me feel weird. My head felt funny and I just felt off. Dazed. So I stopped. I took one a few days ago, just to see, and it was the same weird sensation. Is 100 mg too much for me? Should I take a lower dose or try something else?

• I took 100mg L-Theanine chewing gum for anxiety before tests in college. Never had any reaction. Don't know of a lower dosage.