I have a constant, fairly loud ringing in both my ears, which I developed not too long ago. I'm going to go to the doctors this week, but I'm wondering if s/he will actually be able to help me much, and what s/he will do? Will my hearing get tested or what? Does anyone else have this?

I don't know what they will do to you, but these days they have several different ways to help you out. There have been talk about pills to help, and they can give you a device that you put in the ear that -I think, I don't remember exactly- changes the sounds or something and after a while of wearing it the brain doesn't notice the tinnitus as much.
So there is help to get.
In most cases though the ringing in your ears fades with time, the first period can be really painful, I remember when my brother got it after a consert and had two awful months after that, but it's a lot better now.

they can check to see if there's any treatable causes, such as high blood pressure, or a blockage or growth in the ear. even things as simple as ear wax or impacted wisdom teeth could be to blame. they need to check if they can hear the noise too- sometimes tinnitus can be heard outside your ear, some rare conditions cause that.

also they should test your hearing

it is possible it will go away by itself or you'll start getting it on and off. like babyboredom says, there's a device you can wear that masks the sound of the tinnitus. i think it plays the opposite sound on the spectrum and the two kind of cancel each other out.

i've had tinnitus since i was 5, when i had a head injury, it sucks.

my brother is a drummer and he has had this since his early twenties. i didn't know they could do things to help.

sparkle- as well as the maskers, there's a type of therapy where you train your brain to ignore the sound. i've considered trying that (mine is constant noise, you'd think i'd be used to it but it's still so annoying). my uncle is a detective and got really bad tinnitus from the surveillance equipment, he found it helped

does your brother wear earplugs when performing or seeing other bands? he should do that, and also avoid wearing headphones wherever possible. if he uses an ipod or anything, he should keep the sound as low as possible. otherwise the tinnitus may get worse. also i have heard that if it's induced by noise it is possible for it to get better over time if such noise is avoided.