Thanks for your question.

These spots on your tomatoes could be caused by several different things. Unfortunately from just the pictures you provided, I can’t single them down to one specific thing. Here are some possibilities:

1). Blossom End Rot: This is a common condition caused by calcium deficiency in the plant. It usually appears as a dark, sunken spot at the blossom end of the tomato but can sometimes appear on the sides as well. This condition usually is NOT due to low levels of calcium in the soil. It is usually due to irregular watering patterns. By this I mean the soil dries out and is then watered excessively. Then the soil dries out again and watering occurs. Tomatoes should be watered daily. I suspect that this is the condition applicable to your tomatoes. See:

https://www.canr.msu.edu/resources/blossom_end_rot_tip_sheet

https://extension.umn.edu/plant-diseases/tomato-disorders

2). Anthracnose: A fungal disease that causes small, circular, sunken spots on ripe tomatoes. These spots can enlarge and become dark and leathery. See:

https://extension.okstate.edu/programs/digital-diagnostics/plant-diseases/anthracnose-of-tomato.html

https://blogs.cornell.edu/livegpath/gallery/tomato/anthracnose-on-tomatoes/ - :~:text=Manage anthracnose by controlling sources,Choice (red and orange).

3). Bacterial Spot: Caused by various bacteria in the genus Xanthomonas. This disease leads to small, dark, water-soaked spots on leaves, stems, and fruit. On tomatoes, the spots may become raised and scabby. See:

https://hort.extension.wisc.edu/articles/bacterial-spot-of-tomato/ - :~:text=Bacterial spot appears on leaves,leaf loss can also occur.

4). Late Blight: Caused by the fungus-like organism Phytophthora infestans, this can create large, dark, and greasy-looking spots on the fruit. See:

https://content.ces.ncsu.edu/tomato-late-blight

Of these four possibilities, I believe that Blossom End Rot might be most likely. However, if you are serious about getting to the bottom of things, consider submitting plant samples to a diagnostic disease laboratory for an analysis. This would be a definitive way to arrive at a decisive answer to your question. With that information, you would know exactly what remedial steps should be taken. Both Wisconsin and Minnesota have excellent labs to do this. Before submitting anything to either of them, call first as to what type of samples should be submitted. Both have a nominal charge for their analysis. See:

https://pdc.umn.edu/

https://pddc.wisc.edu/clinic-overview/

Good luck. Thanks for consulting us. Please get back to us with any additional, related questions.