Based on your description, it almost sounds like late blight. Try searching online for late blight photos to see if this is it. How long has this particular plant been doing this?

a pic of the yellow spots

Your containers are too small and I'll bet they are root bound. Just because the tomatoes are small doesn't mean the plant is small. Cherry tomatoes usually grow to about 4 feet tall and and need a very large container to hold the roots. Possibly one with an 18 to 20 inch opening and about the same height. You could probably put both plants in one that size. A large deep pot will also keep them from drying out so the tomatoes don't get blossom end rot as well as growing a flourishing plant. Be sure to untangle the roots if they are root bound. A root bound plant has the roots coiled at the bottom. they more or less strangle the plant. The roots hit the bottom of the container and have nowhere to go so they coil around and around the bottom of the pot. A plant planted this way will continue to coil even though it now has room for the roots. it can't take up nutrients so the plant gets yellow leaves and doesn't thrive. Don't worry if you break off some of the roots but do try to uncoil the bottom. The plant will make new roots. give the planter a bit of shade for a couple of weeks. Perhaps put something against the railing so it is shaded but still gets light. Water it well and give it some half strength water soluble tomato fertilizer. After a couple of weeks you can give it full strength as written on the fertilizer container and full sun.

Pictures of the whole plant and the new foliage that is having trouble would be helpful. It could be a huge range of things based on your description, and the one close-up is hard to contextualize.