Hi, I have a very worrying problem with two of my tomato plants. On April 21 they were fine, April 24 the leaves were curled and the entire plant wilting for two days (weather was cold and rainy, I assumed they were just cold). Two days later they began to yellow, and I added more potting mix and a 1/2 tsp of this fertilizer, I was afraid they were nutrient deficient. I may have over watered them at this point... (approx. day April 26)

Then a few days after that the bottom leaves started to yellow, then it got worse and the left plant bottom stem fell off when I accidentally brushed against it. The yellow/dried leaves are crunchy.

They are in Hortibec Nature Mix seed starter potting mix that was purchased this year. They are indoor seedlings and have only been outside for a few hours last month. They have no grow lamp.

These were taken April 28. They don't appear to be wilting in the day time. I took a look at the roots and they look slightly yellowed. The left is a Chadwick Cherry and the right is a Volkov Cosmonaut.

Photos:

Is it Fusarium wilt? Is it possible for indoor seedlings to get it? I have other tomato plants about two feet away on the windowsill, will they be safe? One plant in that group has a slight yellowing on the lowest leaves (entire part is a consistent yellow) but it is the one furthest away from these plants.

If any more information/photos are needed I'll get it ASAP.

Thanks :(