I found out I have Vit D Deficiency (18) also last month; a new dr checked it where none had before.
I take 120 mg twice daily of Propranolol (Inderal) with no complications along with 1.25 mg (50,000 UI) of D2 weekly and a few other prescriptions.
if you research vit d deficiency; it's very important to keep up with the supplements if you're found deficient
Yes, why shouldn't you?
If you have vitamin D defiency, and you are taking vitamin supplements, the only thing you do is to supply something you lack (and need). Further, if the combination was problematic, your doctor wouldn't prescribe it.
I think you should trust your doctor, and try not to search so much for problems. 5 mg of atenolol is an extremely low dose, I'm amazed if it has any effect at all on anything, but again, your doctor knows and you should trust him.