Tomatoes & Peppers: Please help to identify what is killing my indoor tomatoe plants, 2 by Mypuzo

Mypuzo wrote:
My indoor tomatoe plants are getting sick and I don\'t know what went wrong and what needs to be done to safe these plants. Please see pictures. The leaves started wilting down and yellowing. They feel thin and dry to touch. I was watering consistently; soil is not dry. I fertilized with fish & kelp fertilizer with molasses. One more thing, probably, important mentioning is that I had infestation of what looks like gnat flies (see last picture). To fight those, I treated plants first with Diatomaceous Earth and sprayed with Insecticidal soap. When this didnt help I watered with mosquito bites and sprayed with neem oil. Finally, flies are gone,, but plants are not looking good. Please help me to identify what is wrong and how this can be fixed. I would really appreciate any advice.