(1) Depending on the brake work you had done 3 months ago, you may need it again. If you merely had your rotors machined (sometimes called 'turned' or 'resurfaced'), they may be completely worn out by now. Worn rotors are all dependent on the functionality of your calipers, the wear on your brake pads (or shoes), and your driving style. If you are in a lot of stop-and-go traffic or you do lots of heavy braking, your pads and rotors will wear more quickly. Have your rotors inspected. Machining will only give a little more life to your rotors. Most places will recommend you get your brake pads replaced when your rotors are replaced. Its just common practice, and a good one.

(2) Your grinding noise may be contributed to your CV joint(s) failing. This is commonly caused by tears or leaks in your CV boots. When your CV boots rip, the grease it holds will leak out and allow water and dirt to build up around your CV joints. This wears done your joints and will cause grinding noises. CV joints are not easy to replaces, and can be costly. Have it checked thoroughly.

Another cause for grinding noises can be worn wheel bearings. Wheel bearings are not very expensive, the cost of labor can be. If you have your CV joints checked, and its determined that you need them replaced, have the Joints, Boots, and wheel bearings all replaced at the same time. It'll save lots of money in future repairs.
Good luck!