I hope by now this has started to resolve on its own, and you most likely did/do have some degree of subcutaneous emphysema. This means, as you noted, air escapes (from an unnatural leak) into the tissues, usually around the upper chest and neck, causing some puffiness or swelling, often neck stiffness, etc., such as you've felt, and usually it is not dangerous, but can be very uncomfortable. Treatment is largely aimed at fixing the underlying injury or lesion. In your case it would be an injury, and it's difficult to tell, from here, whether you suffered a spontaneous pneumothorax ("collapsed" lung or at least a small hole, ruptured bullus, in the lung) or possibly a separation in the cartiligenous rings of your trachea. Either could cause the symptoms you describe, although pneumothorax is more common. You mght want to go back and retrace the various stages of the two events, and how you may have been struck, and where. Radiological studies should reveal where the leak took place, although it may have been small enough to have sealed on its own by now.
Sometimes, if there is puffiness or swelling of tissues locally, pressing on the area will produce a characteristic "rice krispies" sound, almost like tiny bubble wrap popping. This is the air bubbles trapped in the tissues popping (and won't do any addiotnal harm, may even relieve some pressure). The goal is to make sure the injury is okay. A "neck injury" in this case, I would think, would suggest a fractured larynx, causing a tiny leak between rings of cartilege, but it's hard to tell, since your symptoms have been fairly nonspecific. These injuries are usually not serious and often will resolve on their own, but should be followed by a physician for sure, with repeat CT scans to make certain the air is dispersing and there's no redsidual leakage. Please follow up with your regular doctor and also keep us updated here. Hope all is well. My best to you.
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist