I have a friend who started balding in his early 20s, and was told that it is due to his high levels of testosterone. He has been lifting weights since he was 15 but that is not necessarily the reason for his hair loss or high T.
Look up stress-related alopecia and bacopa, which is an herb I believe used to treat this condition.
Keep in mind that, if your brother is balding at the same rate you are, it is most likely genetic and not something you can stop. Slow down, maybe.
Prescription stuff I’d look at Avodart, which I believe is dutasteride - Propecia is finasteride - but is sold as a prostate medication, though for off-label use it is given to slow down hair loss.
The reason for off-label use is that it is not directly marketed as a hair loss drug and therefore not considered a ‘vanity drug,’ making it cheaper through insurance. I think 1 mg per day is the recommended dose.
So, take Avodart along with regular use of Rogaine and see if that helps. I’m no doctor but I did some reading on this stuff around these parts and that is what I gathered.
Good luck. I’m balding, too, at 25.