If the medication you mentioned is Amlodopine, can cause flushing. Possible side effects named are swelling, excess fluid in the lungs (pulmonary edema), headache, fatigue, palpitations, dizziness, nausea and flushing.
Some possible causes of high blood pressure include kidney disease, hormonal imbalance, and drugs including cocaine or alcohol. Contributors could be sedentary lifestyle or excessive salt intake.
Your son's doctor needs to do some more analysis of his symptoms and come to a clearer conclusion, and At the least, the doc should adjust his medications.
I'm concerned that a young guy would be put on a drug because of one test. Often people have high blood pressure when they go to the doc. It's a weird anxiety reaction people have, so a lot of people get this. That's why it's useful to get more than one test of BP rather than prescribe meds that can have serious side effects in an otherwise very healthy person, at least as you describe him. I'd want to see him get tested over a period of time. It's even possible these days to get tested at home with your phone, I believe, and while it's not as accurate, if it repeatedly shows he's perfectly normal then it would give reason to suspect that one test. You also said he was tested for F4, do you mean T4? If he was, he had a pretty thorough thyroid test, especially since he has no symptoms of thyroid problems other than this one test. I get that he is having flushing, and I do agree with you that a specialist is probably a good idea, as general docs are, you know, general. But again, if it were me, I'd ask for a few more tests to see if this was a thing. If it were a thing, than you'd be on good ground to try to find out why before just being put on medication unless your doc thinks he's about to have a major event. Which is possible, I wasn't there, but if he does think that, he should have referred your son to a specialist. I agree about calling the doc about the side effects in the meantime. To me, you've got good reason to have concerns, but I don't think a doc has nailed the reason for it yet. Peace.
Familial hypertension is real. I found out that I'm prone to it during my first pregnancy when I had pregnancy hypertension. Normally though, they track BP over a period of time. They tell you to get a reliable blood pressure cuff (I got one on Amazon) and you take your BP two to three times a day at different times and record it. Three months is a good period of time to collect this data for the doctor to them see what is going on. At THAT point is when medication comes into play usually if it it looks like the readings remain consistently high. I also think that diet, losing weight if needed and exercise are essential at controlling hypertension regardless of the age of someone.
I do not think Amlodipine would cause loss of hair but high BP can but most of all stress causes loss of hair and indeed high BP