It's not a clear photo,but has some indication as Alternaria solani ,to give a more close opinion needs other photos of leaves,steam and all plant.For a definitive identification will be better an phytopatological laboratory analysis.
You should defently upload more photos, but because of the black circles respectively dots I guess you look on a virus disease.
Maybe "Tomato spottet wilt virus" (TSWVOO) in a late stage?!
Have a look on: https://gd.eppo.int/taxon/TSWV00/photos