How old is she? Is behavior otherwise normal?
First I would withhold tomatoes for a while, see if it resolves. Anything that causes color change to droppings, particularly red things, can be easily confused for blood. To me it looks like either intestinal shed, or the tomatoes.
Occasional intestinal shed can be nothing to worry about. If it's happening a lot then cause should be looked into. If you can get a fecal float test done that will tell you if you have any internal parasites that need to be dealt with. Worms can cause increased intestinal shed, as well as coccidia. Some vets will do the fecal on chickens, some won't. There are also mail in options that aren't terribly expensive.
https://www.pbsanimalhealth.com/products/fecal-worm-tests-pets