Answer: Based on your description I am not certain what has happened, however there are a number of problems that can affect tomatoes and spread from plant to plant. Some varieties are more resistant to the more common problems than others -- the letters such as VFFNT and so on listed on the seed packet or plant tag would indicate resistances. Here is a link to photos of diseased tomatoes; click on each photo for a close up and decription. You may be able to diagnose the problem.
Otherwise, I would suggest you work with your county extension to obtain a specific diagnosis and then based on that determine how to proceed. They may appreciate photos of the overall plant(s) and close-ups and/or samples enclosed in a clear plastic bag to try to identify the cause.
In the meantime I would suggest you clean up and remove all the infected leaves, and dispose of them in the trash to try to limit sources of reinfection. I would also do this will tomato plant debris/leftover tomatoes at the end of the season. Do not handle the plants when they are damp or wet as this can help spread many problems. I'm sorry I can't be more specific for you long distance.
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