3 full body circuit/3 cardio workouts week.calves and forearm tightness after & during rest not during activity.this compartment syndrome? or creatine

Neither: With extended use muscles tend to swell normally. Muscles are contained in and surrounded by connective tissue sheaths that are naturally restricting. The tightness is normal, not pathologic, as bleeding into a rigid compartment that causes a Compartment Syndrome. Your swelling is normal after the activity and is considered "physiologic." Remember to "cool down" after exercise. That helps.

Multifactorial: Exercise associated muscle cramping EAMC is defined as an involuntary, painful contraction of skeletal muscle during or after exercise. May be due to muscle fatigue. You may also have metabolic/fluid and electrolyte disorders. Cramps from extra cellular volume depletion excessive sweating , electrolyte imbalances eg sodium potassium magnesium, calcium. Schedule appt with Dr for labs and Treatment