In many metropolitan areas there’s a medical practice with a variant of “male medical” in its name. They’ll see whether you need Trimix and what mixture of it - for stiffness of erection, duration of erection or both. The prescription is provided by a compounding pharmacy sometimes within the practice and comes in an injectable form than needs refrigeration. If you can’t find one in your area, skip seeing your doctor and make an appointment with a urologist. He (or she I suppose) will get you started or refer you on. Good luck.