The foam roller is an amazing tool to use to break up those knots/ trigger points. The foam roller is a self-myofascial release.
Self- Myofascial Release: Injuries, repetitive motion, or even prolonged inactivity can degrade the function of your muscles and fascia (the network of connective tissue that surrounds and supports your muscles this results in localized areas with compromised function. Commonly referred to as knots or trigger points. Trigger points are usually hypertonic and tender to the touch, and restrict movement of the surrounding muscles.
The health of this dysfunctional tissue can often be restored through deep-tissue massage/ myofascial release. Applying firm pressure to a trigger point for several seconds helps release its tension and encourages recovery. A massage therapist is an expert at this type of therapy, however the Foam Roller or Rumble Roller provides you with a very convenient and economical means of self-treatment.
Another great tool is tennis or lacrosse balls. They work in the same way but dig in a little further. You could use them against a wall or on the ground.
Have fun rolling away your pain!