Hi there ~
Nightfall or nocturnal ejaculation is a natural phenomenon. I am unsure of what the medications are doing to you. Firstly you might need to consult an psychiatrist
to find out if you have any difficulties in your libido or have other mental health concerns like depression
. Otherwise, you have a very common problem of erectile dysfunction
and / or premature ejaculation
and it can be easily treated with medications available during this time. The class of medication is called phosphodiesterase 5 inhibitors (PDE5Inh) selective serotonin reuptake inhibitors and it also helps with decreased libido which is a result of depression if you are going through one. I advise you to consult with a qualified psychiatrist who might be able to help in this regard. I hope this helps.
Take care and have a lovely day!