Husband's penis still hurts after 4 years-uncut, struggles with ED

I have been with my man 4 years. I'm his first. He is uncircumcised, healthy, we ate both super happy together and crazy attracted to each other. But the position that works for me makes him totally lose his erection. Beyond that, sometimes it's literally painful to him when his foreskin comes back. Any urologist or other MDs on here want to give me an idea what's going on?