What Causes Sharp Pain In The Left Shoulder?
likely muscle injury
Detailed Answer:
HI, thanks for using healthcare magic
The posterior aspect of the lung would be the only organ in that area. Conditions affecting the lungs would usually also present with respiratory symptoms such as cough, shortness of breath etc
It is likely, as you thought, muscle related, this is likely since it improves with the application of heat and worsened with pressure from laying down.
The heat should be continued along with the advil though if the advil is not helping you can try aleve or voltaren.
Paracetamol can be added for additional pain relief. Avoiding any aggravating activities would be important.
If it is very severe then you may need a prescription for a muscle relaxant from your doctor
It can sometimes take at least 2 weeks for muscle injuries to improve.
I hope this helps, feel free to ask any other questions