Have you ever had any problems with your tonsils? This can be easily caused by a problem with your tonsils. For instance if you have infection on your tonsils you might notice some blood in your mucus which is also produced in excessive way. What is the color of blood in your phlegm? If it is bright red then it means that it came from your mouth and the beginning of the throat where the tonsils are. But if the color is dark brow than it means that you have some other respiratory condition which is causing your problems. Have you used any antibiotics to get rid of this problem? You should visit your doctor for some test.
It definitely can be because of tonsils. Beside feeling bump in your throat, you need to observe some other symptoms as well.
For example, if you are dealing with really ugly breath and a constant taste of metal in the mouth, this definitely means that you do have problems that are caused by tonsil stones. When it comes to this stones, they usually appear as a result of either the bacteria getting stuck in your throat.
Visiting your doctor is the smartest option. Do it before it is too late, a lot of things can happen if you avoid visiting your doctor.