There are several possible causes of noises you can get from your bottom bracket.
- Bad bottom-bracket bearings
- Bad pedal bearings
- Loose crank arms
- Loose bottom-bracket cartridge
- Loose chainrings
Of these the loose crank arm (which may be silent or may be accompanied by a creak on each stroke) is probably the one needing the most immediate attention, since riding even 10 miles with a loose crank arm is enough to destroy the crank arm and crank shaft. So you should either check that the crank arms are tight yourself (by torquing the fixing bolts appropriately) or have a bike shop do it.
After that, I've experienced most of the above, but probably the bad (or simply dirty) pedal bearings more than anything else. Pedal bearings seem to pick up dirt faster than any other bearing on the bike (especially when offroad or riding on packed gravel), and unless they are well sealed may need regular disassembly and regreasing. And I've had new, sealed pedals develop noises in as little as 200 miles (though the set I have now have been fine for probably 8000 miles, knock wood).
I did have the bottom bracket cartridge on my current bike start making noise after about 5000 miles (more of an occasional click than grinding). On disassembly the (Shimano) cartridge was found to be badly rusted (even though the bike is only left out in the rain when commuting). Replaced it with a SS Phil Woods unit.
The BB bearings went out on my old Nishiki after a few thousand miles, and on inspection it appeared that the cups had been poorly machined to begin with. (This was maybe 18 years ago.) Replaced the loose bearings with a Performance cartridge.
A bike with only 2000 miles on it should not need any bearing service, unless it's been seriously exposed to bad weather or other severe conditions. But note that 2000 miles is about the expected life of a chain, and yours is probably due for replacement.