We had a whole discussion about that recently, here:
https://www.helpfulgardener.com/forum/vi ... 49#p303749
Someone else wrote in that his/her tomato plants were all burned/discolored, looking like they were dying from the top, the upper leaves.
In that case the OP had also just recently sprayed with an insecticide (Sevin) and a fungicide. I really think (though there are some differences of opinion) that it was the Sevin that burned those plants.
I didn't say anything about it to you sooner, because it did seem odd, that you sprayed all the tomato plants and only one was affected. But Ramona is right, there could be lots of variables. Perhaps the affected one had more tender new growth, that burns easier. Perhaps it got hit harder with the spray -- I think the upper leaves are getting affected most in these cases because that's where the spray falls the most. Or it was more in sun when it was sprayed, etc.