On surfacing, my breathing was very wet and rattly for hours afterward and the cough persisted until the next day. This has not happened before. What you are describing is most likely pulmonary edema, where the lungs suddenly fill with liquid. This is seen in patients with heart failure, though in swimmers and divers it is usually not associated with heart disease but with other factors. However, before you do any more diving it would be wise to visit a cardiologist and be sure that you don't have a heart problem that you don't know about.
Pulmonary edema is unrelated to gas embolism from pulmonary barotrauma or decompression accidents.
Symptoms and signs usually resolve spontaneously over 24 hours. Pulmonary edema can recur, so you'll want to avoid the factors that can contribute to it. I will get certified when I'm 15. My parents are worried about an increased risk of decompression sickness because of my age. There are several caveats, however.