Check under the leaves for signs of red spider mites. Do you see webs? They are microscopic. If you tap the leaf onto a white sheet of paper and see tiny red dots, that's what is wrong.

I don't know where you are, but most tomatoes are about done in this time of year! Even indoor probably don't get enough light/heat. Nancy

I've got fall tomatoes planted in my unheated high tunnel and some plants are developing a disease that I've never seen before. It sounds similar to what you are describing. Several plants have some spots on leaves, but seem otherwise pretty healthy. A few had stems that rotted all the way to the base, and I've found some fuzzy mold on some of those stems.

My two cherry tomato plants had it the worst so I removed them. As I cut the plants apart, I noticed a brown ooze in some of the affected stems. I've been on a weekly spray schedule of Serenade, an organic fungicide. This week I sprayed liquid copper instead, which I think might be more effective if I'm dealing with a bacterial disease.

I'm including a link to an article I found that describes a stem rot disease found in greenhouse tomatoes. This may be what both of us are dealing with. Lack of circulation, high moisture and temps 60-70 help this fungus survive. Those are the exact conditions on my high tunnel right now.

I'm glad to have this little fall crop of tomatoes, because my main season crop this year was so bad, but I figure my tomatoes' days are numbered. I'll be lucky if I get another few weeks out of them. I'm still getting some very good tasting tomatoes, so I'm going to keep them alive as long as I can.

Here is a link that might be useful: Stem rot in greenhouse tomatoes

Thanks for the help! It definitely was red spider mites, once I looked closer I could see them. I mixed up an organic insecticide and it seems to have gotten rid of them but I'm going to keep sprtizing the plant with it for a while.

I live in NYC by the way and have it in a window that gets a lot of sunlight. Before the infestation is was growing quite happily.It has about six tomatoes growing right now. I'm going to try giving it some plant food to help it recover. Wish me luck!

I think having it inside causes spider mites for some reason. I've never seen them outside on maters. Try to isolate it from your other plants so it doesn't spread. We always threw out plants at the garden center I worked at that had spider mites. My boss said they were so hard to get rid of.