If this is the effect of the medictaion given to him in jail, it may be progesterone. but anything goes, a full sex-hormone blood workup is needed esp. prolactin and progesterone and estradiol. he may have high progesterone and prolactin.
I dont ever advocate self-treatment but histamine is shown to lead to early ejaculation since he has delayed ejaculation, this may normalize ejaculation time. I have some other ideas but I think you'd better consult a urologist.
I only went though this problem but my husband was taking pills to keep him awake ...when he was smoking pot it didnt do it but taking the pills it did
Well analytically speaking, if he has a hard time ejaculating during sex he should also have a hard time ejaculating during masturbation.
What happens when he masturbates? You mention nothing about that...
i think better if you talk to doctor that would be the best way to do.