Tomato leaves yellow, some spotted
I've got three tomato varieties growing in containers -- Juliet hybrid, roma, and brandywine. I transplanted them a couple months ago and for a while they were growing really well -- I've been using Fox Farm Grow Big and then Big Bloom.
Now on all three of them, but especially the brandywine, the leaves are getting yellow and falling off. Some of them are spotted with dark patches and holes in them. I've noticed some red aphids (I think) on the brandywine, but just a handful that I've sprayed off -- not an infestation.
Any other ideas? Is this a sign of overwatering, underwatering, overfertilizing, or something else? I'm using big bloom about twice a week.
I've added a link to photos online -- in one of them you'll see one of the central stems of the brandywine, which has gone slightly brown and mottled, although the stem above it continues to grow.
Any help would be appreciated! Thanks.
Here is a link that might be useful: Pictures of tomatoes