I experience a sharp pain in my lower bicep when I'm throwing.
This is what you said.
"Sharp pain" when you are throwing...and then even more after you are done throwing. I'm no doctor but I'm pretty sure that isn't good.
Pro pitchers have trainers that they can do to with their pain issues. When the trainers aren't really sure what's happening or deem that it MIGHT be semi-serious they immediately get that player to a doctor to get looked at (MRI or whatever). Generally speaking, they don't F around with this stuff.
Pitchers that have sustained pain sometimes end up needing surgery. I've known MANY pitchers who have had surgery.
In your situation, you really can injure yourself and/or cause actual damage here. You have no clue what you are doing and are feeling sharp pain when you throw.