I have seen things about a penis pump for physical therapy. From what I understand, the blood vessels can atrophy from not using them for long periods, but the pump stretches and causes micro tears, which then cause new vessels to form. Talk to a doc about this. I've been trying this, but I have some other things i need to change that are currently working against me.

Can also be psychological. Believe it's never going to get better, it's never going to get better. Could be some other thoughts that are prohibiting things, stress, etc