While I agree that a water-soluble fertilizer would provide a quick boost for a nutritional problem, I disaree strongly about using MiraclGro . There's better water soluble fertilizers to use like Jack's Classic fertilizers.
Jack's Classic fertilizers (they have a variety of formulations) are commonly available at ssome garden centers and also on Amazon, directions say to use them weekly and I have used them in conjunction with TomatoTone on my tomatoes for years without a problem.
That said, I think your problem is indeed nutritional, but not any of the major nutrients (Calcium-fortified Nitrogen-Phosphorous- K=Potassium). TomatoTone has almost ALL the major and minor/trace nutrients that tomato plants need.
The clues that struck me: soil with lots of non-broken down wood chips - bought in bulk from a landscaping company, a slow-down/lack of growth in plants and (most importantly) a color change. All leads me to believe your plants are suffering from a combination of nutrient poor "soil", moisture retention/poor drainage caused by the woody "soil", nutrient uptake interference by the decomposing wood chips and the resulting color change caused by a growing deficit in the minor/trace mineral Mg (magnesium, which is at the center of the chlorophyll molecule, where the plants convert sunlight into energy/food; Mg is usually present in sufficient amounts in the ground). All 3 of which I encountered when I began, some years ago.
The immediate solution is simple and quick (noticeable change in color beginning at least by the next day): a foliar MIST of an Epsom Salts solution (1 tablespoon of NON-PERFUMED Epsom Salts dissolved in 1 gallon of water). Spray the solution from a distance, aiming well above the plants so that a fine mist drops down on them: leaves will NOT be even half covered and will definitely NOT drip off the leaves into the soil, creating an toxicity difficult to correct.
If this solution doesn't work: you won't have harmed the plants or increased soil magnesium. But if it does, then mist/spritz throughout this summer whenever you think the plants neeed it. This routine is usually done at 3 growth stages: initially to water in the transplants, again at first flowering and finally at first fruit set.
Your plants will continue to be stunted because of the woody "soil"; I had to replace half the "soil" with a much more expensive high quality bagged soil (gotta love the prices and selection of Ace Hardware, Home Depot and Amazon!) to get normal growth and production the NEXT year. (This also reduced the noticeable nutrient uptake problems.
Keep using TomatoTone (look into adding Espoma Garden Lime into planting holes at transplanting - for its organic calcium) and don't be leery of supplementing with weekly foliar spraying of water soluble fertilizes (I use them especially to boost/promote flowering).
Welcome to the fascinating world of gardening!!
