Another

This does look like early blight. Cut off all discolored foliage and spray a preventative for fungal diseases. If it has not spread too much, it can be managed if you continue with preventative spraying. Google early blight and you will find lots of info. Contrary to the above comment, heirlooms in general are not resistant to blight.

Clavibacter michiganensis pv. michiganensis, which causes bacterial canker of tomato, is very host-specific, so it shouldn't cause disease in other plants. It's usually spread on infected seed, so do not save seeds from your affected plants. If you grew this year's affected plants from seed, I would discard any remaining seed and get fresh seed next year. You can use the soil for other veggies, but don't use it again for tomatoes, even if you live somewhere where it freezes. It used to be thought that the bacterium couldn't overwinter in soil, but now some researchers are saying that it can do so as long as there is decaying host material for it (which would include tomato roots that don't get pulled up, any foliage or fruit that you miss which decays in the soil, etc.). So to be safe, get fresh soil for your tomatoes next year. Your containers shouldn't pose a risk next year if you clean them and disinfect them (bleach solution should work well). There is no record of infected fruit harming people, so I wouldn't worry about it, but don't can any fruit from affected plants. Many diseases alter the pH of fruit, and if the fruit isn't acidic enough, canning it can be dangerous

I'm sorry but something is effecting the root growth or the roots ability to take up nutrients for that one plant only. Either the plant or the soil below it and is what I tend to suspect. I looked at the fertilizer analysis of the miracle-gro and mixing instructions and really don't see a problem on your part. My first thing I thought when I looked at your pictures was a potassium deficiency and/or a Magnesium deficiency but your fertilizer has Magnesium in it and potassium, (but not enough) and you're not OVER fertilizing it (toxicity) so I may be stumped here. My only suggestion now is to Take 3 TABLESPOONS of the miracle gro and mix it with a quart of water and feed that one plant only with it all at once. I do know the miracle gro you use lacks enough potassium for tomato plants with tomatoes hanging and the subject is taken up by myself in detail in this Houzz topic. https://www.houzz.com/discussions/5732208/what-s-wrong-with-my-tomato-plants#n=3?hz_ref=aHR0cHM6Ly93d3cuaG91enouY29tL3w5ZGE4NmUwNi1lNTRjLTQxYjUtYmMxNi04ODFiYjdlZDg1MWV8MTU2MjA3ODM1OTE1OQ Included are pictures of a few of my tomato plants. Again, sorry and good luck.