I could be wrong….it's tough to make a good diagnosis on description alone. A muscle spasm typically comes in the form of some of the muscle fibers within a muscle being in a state of fused contraction. It will give the sensation of tightness through some ranges of motion and can be a result of anything from electrolyte imbalances to nervous system dysfunction. In contrast to a muscle spasm, a muscle pull refers to an injury to the muscle itself. Muscle pulls are often accompanied by muscle spasms in neighboring muscles as the body attempts to protect itself.