If you had a torn/rupture trap, there would be a very sharp pain at that very moment it happen and the muscle would roll up into a large ball. Also a immediate discoloring (purple/black, which is blood pooled up under the skin). Sounds like you may have a muscle knot (not that uncommon), which can be related to a muscle spasm and lead to inflammation of the area.
Might try doing a light massage yourself, but it will cause pain, if you can get past that. Can get a sports massage, or Rolfing, from a professional, which might be a good idea if the problem persists. If nerve damage, than suggest the latter. Even acupuncture or spinal/neck adjustment might apply in your case. (I'm very big on spinal, back and acupuncture treatment..preventive or otherwise)
A slower method is heat, which can work well with your self massaging. Still some debate about the use of heat or ice. Might suggest alternating heat with the ice treatment., which a majority of trainers do. Or try the more nature method of allowing the injury to heal by it's self, which it usually does. Good Luck.
Big thanks for your insight and expertise jpm!
I went to another doc today and getting an MRI will take while - tomorrow I'll head back to the hospital's ambulance for a re-check.
The hurt region now starts to feel VERY sore and still has little activation -> left trap rounds right/hurt one feels weak and looks flat. No knot so a level 2+ pull seems most likely.