Beginner Gardening: Help for my sickly piper methysticum (kava kava), 0 by Schez

Schez wrote:
Here's the info:

I ordered this plant from HI about three weeks ago, it arrived safely and in good condition. I repotted it about three days after I got it, using organic potting soil mixed with Perlite in a terra cotta pot. When I repotted it I had to snip away the roots growing around the bottom and the sides of the original pot, as they'd begun to make rings around the container (it was underpotted).

It sits in a south facing window between two other houseplants. It gets about eight hours of sun a day, and I've added a cheapy grow light to help it squeeze a few more hours of light in. I water it every 2-3 days (or whenever the soil starts to feel dry around the roots). I don't fertilize it.

The plant thrived for a few days. Then the newest leaves started to crinkle along the edges, form holes throughout the leaf, and got a washed out look to them. I snipped three of them when they started to die. Now the older leaves are starting to do the same thing. Also, the leaf stems are forming cracks in them. I'm starting to get worried. I wonder if I'm over/under watering, have pests, or if the plant is maybe getting too much sunlight.

Any help would be much appreciated.