I've been growing a lemon tree from a store-bought lemon seed for about half a year now. A few days ago the temperatures have started to increase and since then the tree looks dried out, even though the soil is moist and has been watered regularly.
Since I was suspecting a heat stroke, I've placed the plant inside in half-shadow, but nothing seems to happen already for around a week. The leaves aren't crispy, but just curled up. I've fertilized the soil and also placed it in an open, north-facing window to provide some air movement. Also increasing the local air humidity with a tray didn't seem to have any effect so far.
What exactly is wrong with the lemon tree? How can I rescue it?
On the internet I found that this might be an issue with the roots. Can I trim them somehow?