I have been suffering from episodic clusters for over 13 years. For me, prednisone works for the most part, but can have serious side effects over time. Oxygen only helps when the pressure first begins to build, and even then it's hit or miss. Exercise can decrease the general pressure, but doesn't do a damn thing once the real pain begins. The only thing that has been able to stop the pain dead in its tracks is imitrex. It took years for the headaches to be properly diagnosed, and several years after that before I was introduced to this lifesaver. I have taken it in two forms - subcutaneous injection (generally in the thigh) and pills. The injection works within minutes, the pills take slightly longer but are more work appropriate. The only time in 13 years I have experienced no pain, no pressure, no hint of a headache, are the minutes to hours after taking sumatriptan (imitrex). If you have not yet tried it, ask your doctor if it is an option. It is the only thing that has ever helped me.