Is My Tomato Plant a Goner?

We bought this Early Girl tomato plant and it was doing really well for awhile but it took a bad turn and haven’t figured out how to fix it.

We live in Southern California and it’s placed on the southern wall of our house so it gets plenty of sun. One mistake I learned from this sub was not to water the leaves and starting watering just the soil.

One hornworm, but that was all I found on it.

Any suggestions would be much appreciated.