Hand Pain + Future Working Out

Hey guys! How are we all doing today?!

So, out of nowhere, I suddenly started having pain in the area just underneath the base of the thumb (I've attached a picture) and it hurts every time I've moved it. I am able to move the thumb but it hurts a lot. I'm currently in the last week of FBStrong, and have been lifting weights a lot more than I usually would and that's because I've been wanting to get into strength training a little bit more. The reason why I came to the community page is that I don't know how to go about healing the pain. I have no prior experience with this whatsoever. If anyone reading this has been through this or something like this before, then please do not hesitate to reply. My main questions are: What could it be? How do I go about fixing it? And how long will it take?

Noor A