Trimix/Bimix/Caverject/Edex all work with no nerves. The drug causes the blood to rush in and engorge your penis. The aching pain comes from the Aprostadil which doesn't affect some guys, who are extremely lucky as far as I am concerned. You can have a low Libido or no Libido and Aprostadil will work.
I would follow your doctor's advice although I have found that if I miss the correct spot when I inject, I don't wait a day. I simply go to the other side and give myself another injection. However, I'm using really low doses of the Trimix and an extremely small,short needle.
Taking Ibuproven before injecting will help with the pain. I usually take an Advil before I use the syringe. Btw, like others on here, I have found that I'm needing a smaller and smaller dose as time goes by.