Symptoms: My pictures have a dark spot on them. It is in the same place on each photo. The only time it changes appearances is when I shoot at F22 the spot is more crisp and defined. Whereas when I shoot at F4 the spot is out of focus.
Objective: DSLR camera is otherwise functioning correctly. Camera was taken in the desert for a weekend trip and it was a bit windy. Camera lens was changed while outdoors. Camera is 1.5 years old and has not had the sensor cleaned.
Assessment: The sensor has dust on it due to normal wear/tear. Conditions of changing the lens outdoors in a windy desert likely the time of onset, due to opening up the inner workings of the camera to outside dust particles.
Plan: First, try the self cleaning menu option on the camera if it has one. This can work if the dust is lightly attached. But more often with the visible dust particles, it will require manual cleaning. Refer to your owners manual for opening the mirror and/or manually self cleaning. If you are a DIYer: watch a couple of youtube videos, decide what method/tools you want to try, and clean the sensor at home. Or if you are more comfortable with sending it in, take it to a reliable camera store and who offers sensor cleaning. Whatever you select, remember that this sensor is your permanent 'film'. You only get one per camera.
Personally, I have cleaned my own sensors and for other people at times. I have taken a rubber spatula from the kitchen (don't tell Amber) and cut it to the width of the sensor (you can find that here). I have used rubbing alcohol but would probably get slightly better results if I used some Methanol (harder to find).
I ensure that I use a new cleaning cloth each time I clean the sensor. Here are a couple of videos that I have found helpful.