I am a healthy being. The docs told me that since the puncture is on the upper part of the left lung and according to my symptoms, it must've leaked through the part of the lung that faces my back, applying pressure to my ribcage and chest, causing extreme pain on my shoulder area and arrythmia due to the heart having to cope with the applied pressure. My heartbeat returned to normal with some slight rapid beats but nothing worrying. My shoulder stopped hurting due to the medication I was given and was told to continue normally and next thursday I will get new exams to see if the lung returned to normal, it stayed the same, or worsened.
I knew it was pneumothorax but speaking spanish, I was unsure what the translation of "neumotorax" was so I basically used what the injury is.
I was also told that it's common with traumas near the ribcage, which wasn't the case, and somewhat common with tall and skinny people around the age of 18. I am about to be 18, am 180cm and weight about 65kg so I fall into the latter category.