Not that im an expert or anything, but Ive spent enough decades of my life training for peak physical performance and that sounds EXACTLY like a pulled muscle!
A muscle strain, tear or pull is not something to take lightly when lifting heavy like you are or performing to peak ability. That muscle/muscle group either fatigued under strain and tore, ripped or pulled on other muscle groups because at a given moment it was the weaker muscle, and now other muscles are working harder to gaurd the damaged muscle so it can recover.
Not to preach but damaged muscles rarely come from "lifting too heavy", actually forcing a muscle to do something it physically can't do (you straight up fizz out before actually tearing something because the weight was too heavy) but rather not having the proper nutrient/fuel and hydration for the muscle to do/continue to do the work being asked of it when it's doing work its capable of... And recovery speed is also limited by nutrient/hydration intake... And rest...
Stay hydrated! Eat high nutrient foods like sweet potatoes, chicken, and quality greens...rest and stretch those muscles! You can work with light weight and lots of stretching, but if you're experiencing the pain at a certain weight, I'd stay away from that weight as your muscles are definitely sending you a message, and its not push me harder...
If it were me I'd get on a sled or leg extension machine and allow a machine to guide and gaurd my efforts until I was fully recovered and Id use machines and light weight squats until I could blow thru the weight you're struggling with now...