There can be a problem when seeking more panic when the prevailing fear is "passing out" especially when driving a car or in some other immediate situation. Actual fainting is a medical problem.
But remember not to confuse fainting with lightheadedness. Most panic attack sufferers experience lightheadedness or giddiness every time. Are you a hyperventilator when anxious or in a panic state? When you are breathing rapidly you are taking in too much oxygen and not enough carbon dioxide. This affects your blood acidity and it makes you lightheaded and feel faint. Also your tension affects the muscles of the neck and eyes and this can create the sensation of lightheadedness. Panic attack sufferers WORRY about fainting but rarely do. This is a common worry during the onset of panic attacks. After more experience many individuals lose the fear of fainting because it usually doesn't happen. If you are a hyperventilator then try breathing into a paper bag or even into your hand to increase the carbon dioxide in your lungs. If you are worried about passing out try to make yourself faint while sitting or standing in one spot. Not so easy to do when you WANT IT to happen!.
The human body has zillions of processes going on all at once. Occasionally "something" can go amiss such as rapid drop in blood pressure from standing up too quickly. But the human body is also a repair and maintenance facility. The body knows how to survive. It will always try to correct itself. You can have faith in your own body. Your fainting episode many times is only temporary. There is nothing wrong with you!
Some people who actually faint or nearly faint have a low blood pressure condition. But once the fear kicks in, in these cases, the blood pressure rises and the feeling may decrease. Some others have had a temporary medical condition such as a viral infection, allergy, vertigo from an inner ear disorder, anemia, sinusitis, heat exhaustion, poor eating habits, low blood sugar, salt depletion, etc. that may result in the feeling of, or actual passing out. This usually goes away over time despite the fear of it.
What to do if you have actually fainted during a panic attack? Visiting a medical professional is the first thing. But our medical professionals don't always have the time or energy to be medical detectives. If there is no obvious physical problem then they may prescribe anti anxiety medications - which may be a solution for some but a problem for others. Keep trying! Seek out information about those medical professionals that are more innovative and detailed in their work. Don't accept a pat answer of "anxiety" always. You need to be convinced that the medical profession has done all it can for you.
Another good option is Cognitive Behavior Therapy (CBT). This therapy takes you through the steps of desensitizing your reactions and giving you back control. Many times a combination of meds and CBT can solve this fear of fainting (when there has been actual fainting) in panic disorder.
But remember, ACTUAL FAINTING is rare in panic attacks. When this feeling arises the natural tendency is to tense up and want to run out of the room or whatever. The opposite works much better. Relax and let the feeling come all over you. Go with it rather than fight it! Let yourself faint if that's what you fear. Try not to overreact and blow it out of proportion. A relaxed body is not conducive to fainting.