My orange tree is messed up!
We viewed your photos. The photo on the left looks like you may be dealing with nutrition issues. Give actively growing citrus a high-potash, tomato type fertilizer every two weeks. If the light intensity is poor during the winter, feeding is not recommended until the light improves (usually March through September).
Watering - while the plants are actively growing, alow the top inch of the mixture to dry out between waterings. In any resting period (winter) water only enough to keep the mixture from completely drying out.
Repotting - You can move the plant into a container one size larger each spring until maximum pot size is reached. Then an annual top dressing of fresh potting mixture is recommended.
Move outdoors in the summer. They like bright light.
Middle and right photos - The photos are out of focus. It is possible you may be dealing with a type of sucking insect but we cannot say for sure. Look for honeydew, stippling, etc. Take a look at our website for photos of possible spider mites, scale, etc. http://extension.umd.edu/hgic/topics/spider-mites-houseplants
Here is more information on citrus https://web.extension.illinois.edu/cfiv/homeowners/080110.html
Look on the undersides of the leaves for possible spider mites and scale insects.
Thank you very much for your answer. I will certainly keep your recommendations in mind.
Now, with respect to the Middleton and left pictures issue: I have attached to this answer new pics, better focused, for I have not found any coincidence between the wounds my plant presents and those that are posted in your website.
I will inspect the undersides as well.
This looks like physical damage to the leaves. It is possible that they could have been torn when moving the plant or if something bushed up against them to cause a tear. This does not look like something caused by a pest or pathogen.