Try plugging them in to something else and see if they work normally.
If not, the driver is probably going out, or the connection is loose. You can't really fix the driver, but the connection can be fixed but it's moderately hard to do.
Pretty much just buy some headphones and this time don't cheap out. Don't buy a headset, they are usually overpriced due to the fact they mashed some bad headphones into a bad mic. If you do it right, you should spend a good amount of the headphones and like 5 bucks on a mic.