I hit my right leg on the car door on the calf area and it bruised for about 3 weeks. The discoloration and pain contiued so my doctor did a ultrasound and no blood clots were found but its been 6 months and the area is still dark and sometimes painful after workout or a lot of walking. I have been holding warm moist heat to the area and taking asprin.
The healing process results in laying down of new tissues and fibers at the bruise site. The new tissues will take some time to get back to same level of strength that was there in unharmed part. This might result in occasional pain, especially with high intensity workout. You should stop applying heat. Instead of aspirin, apply local diclofenac gel as and when required as it is safer.