UFO Sighting in Chicago, Illinois on 2017-07-22 17:40:00 - Black object appears in one of my photos.

Hello, i don’t know if there were any reports of ufos over or near chicago on saturday, july 22, 2017, but i was out on the chicago river (at the crook of the n/s branches) before sunset and i captured something in one of my photos. i’ve never reported anything like this before but i am curious to know if there might’ve been others that witnessed something in the skies over chicago around 17:40 cdt. i am attaching the photos to this so you can see that near the building in the middle (300 n. lasalle) near trump tower, there is a black object there that i can’t describe. i didn’t notice it until i reviewed my photos later. i usually take multiple shots in a row and in the previous two, it’s not there. unfortunately this object is in the last burst shot (for 1/400sec). it’s not a dirty lens/sensor, because i would’ve seen that in the previous shot. upon zooming in the photo, it doesn't look like a jet, helicopter or even a dirigible; it's nothing identifiable. please can you help me identify this object? after i reviewed my photos and saw this, i was at a loss of words. i didn't notice this outside of the photos, just after i reviewed my photos.