Hi Kevin,
Sorry to hear about your Mac overheating! Fortunately, this is a very common issue among many Mac users and there quite a number of discussions on the forum regarding possible solutions. In order to best solve your specific situation, it would also help if you could provide a bit more context information regarding the 2015 Mac and the conditions it has recently been exposed to.
Did your Mac experience any repairs or modifications recently?
Have you had any software updates recently?
Has the computer experienced any physical or water damage recently?
Where do you regularly operate the computer?
Does the computer overheat and shut down immediately or is it a gradual process?
If you could maybe answer these, or provide some additional info, it would definitely help narrow down what the specific issue is with your Macbook and how to fix it.
That being said, first try resetting the SMC on your Mac and see if that produces any results.
https://support.apple.com/en-us/HT201295
If no results, the problem may be due to the heat sink and thermal paste in your computer. I have provided several links concerning similar situations and you are more than welcome to search our answer forums for the solution. That being said, the more context information that you can provide regarding the product and the product issues the quicker we can identify the problem and work towards the solution.
[post|183340]
[post|1415].
[post|128091]
https://macpaw.com/how-to/how-to-fix-an-overheating-mac
Hope that helps!
Best,
~[ID] Sep 06, ''2018''