I woke up this morning and my penis was unusually small. In the shower I attempted to stimulate myself and found it was difficult to gain an erection. After some effort I was able to but it wasn't exactly solid.
What could cause this ? I took a normal dose of otc Robitussin the night before to relieve congestion. I am sexually active and am a light drinker/smoker.
this is still persisting as I type.

You may masturbate too much and then your body my be extra relaxed due to the robitussin.

you wasnt in the mood