Well there are a number of possible causes that a photo alone won't ID. So we need much more info please. These are in containers correct? What size container and what growing mix is it filled with? How much and how often and using what product have you fed them with? That will help eliminate nutrient issues I see.

Next where are you located, what are the ages of the plants, have they bloomed or set fruit yet, what pest did you see to make you think that was the problem (check the underside of the leaves very carefully for tiny pests), and what exactly did you spray with. (For future reference you never spray them UNLESS you see actual pests. So called natural pesticides can be just as harmful to plants as synthetics are when used wrongly.)

Lastly, are all your plant equally affected and is it all over the plant or only on a few leaves? If so what has the weather been like recently? All of the common tomato diseases require certain weather conditions to thrive.

I suspect you may be dealing with a couple of possible disease issues but those same symptoms can have other causes too so need more info.

Dave

If that is on the lower leaves, especially those towards the sun, then it's magnesium deficiency.