Hello and welcome to MedHelp's forums. Thank you for your question. This is a bit hard to determine what is going on. Whether it is due to that initial visit or not is hard to say. My suggestion is to see another doctor. You can have different things going on with regards to chronic anal itching. Here's a helpful slide show. https://www.webmd.com/digestive-disorders/ss/slideshow-anal-itching.
If the doctor did not wear a glove to examine your anus, this would be quite unusual. That generally is protocol. If he neglected to wear a glove, this may be the reason for his stand offish behavior when confronted with this. But if he did not, that could possibly put you at risk for things like a fungus or bacterial infection. Otherwise, there are several reasons you could be itching.
I don't think you'll ever be able to prove the incident happened because of the doctor visit but instead would switch focus to just solving the problem. Look through the list of possibilities. Being ruling them out one by one with the hopes of finding the true cause. Let us know how it goes.