It would have been prudent for her, as for any diver, to do an annual Fit-for-diving medical.
If her problem was EIB, a standard medical evaluation might not have been helpful. A little background about bronchospasm, to help people here sort out all of these conflicting opinions. Remember, all of this speculation is based on incomplete data, and self reporting by an admittedly upset, anxious and possibly disoriented reporter. Thea, please understand that this last point isnt an attack on you, its just that from your narrative and from the video, its hard to assume that what we have to go on is an objective, third-party report of all of the events and clinical data. Whether the inciting event was medical or panic, either way you certainly were upset when you wrote the OP, and it sounds like you were more so during that day. I myself had a lot of trouble precisely reconstructing the chain of events leading up to my DCS episode, and it took a long time to get it right.
The large airways (the trachea and proximal bronchi) that bring gas to the part of the lungs that actually exchange oxygen and CO2 (the alveoli) are made of cartilage, and have muscle in their walls. That muscle contracts normally in response to a number of stimuli. Sometimes, the contraction is excessive, causing bronchospasm (in which the muscle clamps down and narrows the tubes). This makes it harder to move air in and out of the lungs. Reduced bulk gas flow primarily affects CO2 elimination, since O2 diffuses more rapidly and its transfer to the blood is less dependent on ventilation. However, severe bronchospasm can also cause low oxygen saturation as well.
Now everybody has this muscle in the wall of the airway, and everybody will go into some degree of bronchospasm given the right stimulation. Three classic triggers are cold air, dry air and dirty air. This is why people with nasal obstruction are prone to bronchospasm - the nose warms, humidifies and cleans the air of dust and other particles. Hopefully, the air in our tanks is clean, but its still relatively cold and dry. People who have asthma (the modern term is reactive airway disease) are simply those people who are excessively sensitive to triggers like this, but if you take almost any person and have them run on a treadmill in a cold, dry coal mine they may wheeze as well. EIB is simply bronchospasm associated with exertion, in a patient who doesnt have asthma at baseline.
To really diagnose EIB, or any sort of RAD, you need to do pulmonary function tests (like measurements of a flow-volume loop), often with and without a challenge (a drug that induces bronchospasm). Just like a stress test for the heart, you are looking for an event that might not happen commonly but that you want to study in a controlled setting.
Treatment of bronchospasm relies on bronchodilators - drugs that reverse the excessive muscle activity in the airway wall. O2 can help someone who is hypoxic to feel better, but it wouldnt necessarily reverse the underlying problem. People who are chronic asthmatics, or who are prone to EIB can also take medication to stabilize the airway muscle and prevent these problems.
So Thea, if you might have had EIB, and you really want to continue diving, you need to have this formally evaluated by a pulmonologist and determine if the diagnosis is correct and if your condition is something that can be managed medically before you get in the water again.
But I would add my voice to the others who have pointed out that there is more to your story than just an unanticipated medical event that hit you out of the blue. For what its worth, if you are to return to diving, think about dive planning, the role of your buddy, the role of the DM, the implications of an overhead environment, the implications of buoyancy control and an uncontrolled ascent, and the need for the ability to do standard procedures like inflating your BC on the surface and dropping your weight belt, even if you are experiencing discomfort from other sources.