I have had this problem as long as I can remember but when I got to about 30 I changed from briefs to shorts. At least your stuff has some room to move. Then as I got a bit older my balls started complaining and needed frequent discomfort adjustments . . . so the constriction of briefs was one problem and then the lack of support from shorts became another.
I particularly loathe the double fabric that they use in most men's briefs. What is that all about? Presumably for people who are worried that if they put it away too soon it'll leak onto their trousers without an extra layer of protective fabric!. Still I find it uncomfortable and I'd rather wait a bit longer and give it a bit more of a shake!
Anyway. I found some underwear advertised in the UK magazine Attitude that are just great! The brand is "BIGBOY". They point out that you don't require a big dick for these, they're soft and stretchy, and they just happen to support whatever goes in them, including a big dick and big balls without any problems using a single seamless layer of quality fabric. I get them from the UK for [Brit Pounds] 11.99 which is AUS$22.50, [the website is:
http://www.attitudedirect.co.uk/shopping/home.php?cat=449]. But you can also get them from the US [
http://www.dealbyethan.com/index.php?main_page=product_info&products_id=5915]. They are US$19.90 or $22.94, which is slightly more expensive than the UK price, but the US suppliers have small discounts if you get a few more [which is good, so you can have some in the wash, some in the drawer and a pair doing their job!].
If you get some just get one pair though [as they're not all that cheap!] and see how they fit generally. In all these things it's incredible how different things wrap around different guys! I got the biggest size, but I reckon that one size bigger would sell a million!
I've also thought of trying the COCKSOX brand which are about the same price but they seem to have a seam at the very front and to be more about showing off your bush than supporting your cock and balls. I see that males pubes are coming into fashion witrh the new Levi 501 Jeans but I just want something that isn't ever gonna leave me feeling half dressed. I'd be interested in the brands other people have tried.
The first time I tried BIGBOYS jocks on I felt comfort like I haven't felt foir a long time. And they pack things really nicely from an aesthetic point of view too!