Hi. for many years now, i 've been getting intense and utterly debilitating pain and pressure behind my left eye that seems to come in clusters. for a variety of reasons, i am pretty certain they are cluster headaches. can this app help? no insurance

You may be right: If you do have cluster headaches and are otherwise healthy, consider going to a free clinic for at least one visit. If the diagnosis is correct, they may be able to provide you with free medications, or give you a prescription for something relatively inexpensive that works. Bear in mind that "works" means "works pretty well most of the time." Don't expect a magical pain pill.