Since blisters traditionally come out of an activity which you participate in on a daily basis, or on a regular basis, this kind of dream signifies that you have been annoyed by something that has become a part of your daily activities. This is not to suggest that one of these activities itself has become more annoying than good for you. What this suggests is that some element has occurred now that causes a small annoyance during your practicing of this activity. For example, if you go to work every day and it has been fine, but suddenly a new employee was hired whom you don’t get along well with, this would make your overall completion of your work very much more annoying than it was before.
To dream that you have a blister on some area of your body suggests that you have been overworking that area of your body recently. Perhaps you should calm down on all the guitar playing and set aside the drum sticks. While the blisters can be a great motivator to keep you playing through the pain to get to your goal, they can also just seem to make the overall doing of that activity severely annoying. If this activity is something that you are very passionate about or something that you genuinely love doing then you should not allow the blisters to hamper your enjoyment. No matter how much you enjoy it, it can be a good idea to take a break every once in a while. This might be a warning against doing something too much.
Remember the saying that too much of a good thing can be a bad thing? If you do something that you like too much it can lead to a blister which can make the doing of that thing a tough and unenjoyable experience. A dream of blisters could suggest that it is time to cool down on practice for a bit and instead try out some other things or focus your energies elsewhere. This will lead to more enjoyment in the future when you pick up that hobby again and will also allow you to appreciate it more since you will be fresh at it again and not feel so worn out.
If you dream that you have blisters from doing something like playing the guitar, this could also be an encouragement to continue though. No matter how annoying blisters are, if you keep getting blister after blister forming on top of one another it leads to calluses which make your skin stronger while shaping them in a different way. If you really keep at it then your calluses can be a sign of dedication and show others that you are serious about what you do, your dedication is a serious one and what you are doing really matters to you. Some people wear their calluses like trophies and a blister is your first step on the way to a sweet new trophy.