The fact that these bumps seem to come and go without much trouble and don't really hurt suggests that they are not very serious. However, if you are worried about them you could show them to your primary care doctor
or your dermatologist
The most likely possibility is that you have some small cysts in the earlobe. These tend to come and go in size like you have experienced. This is because many cysts have collections of material inside them and this may accumulate at some times and not at others. The important thing is not to pick or squeeze at them, as this may irritate them or cause infection.
If one of the areas ever because very large, painful, or has reddened overlying skin, these all may be signs that the cyst has become infected. In this case, it would be advisable to have the area checked out by your primary care doctor as soon as possible to determine if it needs to be lanced or treated with antibiotic medications.
If, however, you never have any of these concerning symptoms and the areas are not particularly bothersome to you cosmetically, you can just forget about them and not worry