Popped My Lower Back & Relieved Intense Pain

A few years ago, I (28M) had my second back surgery. It entailed a fusion of two of my lower vertebrae. Forgive me I dont remember which two. All in all, its prevented me from doing most of the activities I love doing. Golfing, disc golf, bowling, bouldering, etc. Yesterday I deviated from my norm and went golfing. After playing I had arguably the most intense, dull pressure, back pain i’ve ever experienced. (Minus immediate post surgery.) The pain basically ran from shoulders to butt. I’m used to lower back pain, but it generally stays localized. Sitting at my desk today, I squeezed my legs together and in doing so, there was a loud POP, that came from my lower back. For a moment it was an intense pain, followed by relief. All of the pain was immediately gone. (Minus my regular day to day pains.) Any ideas what may have caused this pain and relief, or whether it should pose any concern?