Roleft said:

I have two potted tomato plants that were thriving, but now are failing. One is
a cherry tomato plant that was yielding LOTS of beautiful and tasty fruit.
After the first large batch, the leaves started turning brown and yellow and
there has been NO more new growth in several weeks...not leaves or blossoms. I
have fertilized and both are planted in a potting mix.

What size pot? Your plants may be completely root-bound.

In my experience, the most fertilizer for potted plants is Osmocote (or a
similar 'off-brand' product). It's an encapsulated, slow-release fertilizer
that can't be easily leached out of the pot.

snip
We have had LOTS of rain in the past few weeks (I live in SE Kentucky) and am
wondering if root rot could be a problem. If so, can this be resolved?

Drill some holes in the base of the pot (if there aren't any there right now).
I've never had to worry about potted plants get overwatered before -- usually,
the opposite is the problem. (Last month's record rainfall only meant that
I didn't water the couple of potted plants that were out there at all.)

--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)