R.S.
One of my first "ah ha, I am really an adult now moments" was when at college (I was 18) and I was sick and took myself to the doctor, then they wanted to draw blood and I walked to the lab calmly and waited and allowed them to take blood and then drove myself home...no muss no fuss...
That was when it hit me that I was "grown up". Took myself to the doctor and got bloodwork alone.
He needs to grow up...he is 19 and sick...you can read this to him if you want...is he a boy or a man??
He needs the bloodwork done...remember that blood test I was just talking about...it showed my red blood cells were so low I could have started bleeding from my nose, eyes and other places if they had waited...I got back to my dorm to a message from the doctor to get back to the clinic asap. I needed to be monitored aka hospitalized...I did that alone too until my friend got home from class and met me...then my mom drove up to be with me.
So you mom...get his butt back to the doctor and get the tests run!!!! it could be any number of things...mine was a mono like virus (never tested positive for mono...but it mimicked the symptoms and was a very bad case!!)