you need a prescription from a US pharmacy to sell it you. Most of those adds are herbal and not found proven to be effective. You are correct trial and error is not the way to go.
If you have not followed David’s advice please do. If you have venuos leakage, high estradiol, neurological disorder, or a number of other issues unknown to yourself. Taking these meds improperly can do more damage than good.
Your doctor will give you a free sample after the examination. If he/she is any good they will want to do some blood work. The most important thing for you is to tell your doctor everything. This is not something where information should be withheld. I also advise seeking a local expert amongst the doctors. You can spend a lot of time and money bouncing around to get proper treatment.
You will also do better to post your symptoms and what your experiencing. It will help those within the group to convey their wisdom should it pertain to there experience.