If you’re a gym rat then what you’re experiencing might just be ‘DOMS’. This is ‘Delayed Onset Muscle Soreness’ which essentially describes the normal muscle pain that we tend to feel after an intensive workout.
It’s not entirely certain what actually causes DOMS, though it is agreed that it is likely to be to do with the build-up of metabolites or damage to muscle fibers.
Either way, it should go away in time. The best treatment is actually to engage in more exercise targeting the affected area!