Sorry but I can't see anything out of the ordinary that screams infection or injury and what I can see up close is so blurry it is very difficult to even look into detail. I would say the best thing is to observe your snake for signs of that darkening getting worse and signs of any infection. If you grow concerned that it is becoming worse, the best thing to do is to find a vet in your area that handles exotic animals and make an appointment. They should be able to educate you on the proper treatment methods for a mouth infection and give you medication to help treat it.
Good read on mouth rot and some ideas on how to improve husbandry to prevent it from happening. My thought is there is no signs of disease or necrosis so the best advice is to just observe and make sure you are following proper husbandry at all times.
http://www.peteducation.com/article....+1796&aid=2385
Also to help with how to link from your chosen hosting site:
This is a link to the page
https: //ibb.co/cLzGw5
This is a link to the image on that page
https: //image.ibb.co/cxqOb5/IMG_0334.jpg
You would do this by either finding suggested link options when you upload like imgur has or by waiting until it loads the page then clicking the image to expand it then right clicking and choosing view image (btw using imgur.com is 100x easier)
You would use the above .jpg link to add via the insert image button on the editor.