Hi folks, I'm a new gardener and this is my first year planting, ever! I was doing great and so were my tomatoes until I started to see yellowing leaves. I thought I wasn't watering enough so I added a little more water to my routine. Well, this is what they look like now. Can anyone give me advice? I hope it's not early blight!

I'd hate to lose this plant and the 2 next to it, especially since I only planted 3.