Could it be a Muscle?
You're right, your pain could be coming from a muscle.
It could also be coming from a joint, a ligament, a tendon, some fascia, a bone, a blood vessel or just about any deep tissue.
In reality, "classifying" your pain adds nothing to your healing process, but having a clear nerve system does. Why is that?
Tissues devoid of animating life cannot repair or heal. If you cut into a LIFELESS steak (a muscle) and it will never mend. Injure a LIVE body part however, and it will reorganize itself successfully as long as it receives information from the nervous system - regardless of what sensation you feel.
When information flows freely - you heal.
When it trickles - you don't.
When it stops- tissues die.
As Chiropractors, we have compassion for any discomfort you have. But realize, while naming your "tissue of pain" (diagnosis) may provide some peace of mind.... detecting and correcting the cause (adjustment) will help restore your health by keeping the information flowing freely.