I know it is a concern of ours when we volunteer for events such as walks or runs... but it is beyond our scope of practice to advise them on anything other than seek out the first aid station, keep it clean and covered... and DON't POP IT!!! Unfortunately these are things that they will ask us, because they are sitting in front of us looking for comfort and treatment. But definitely refer them to the proper area which isn't us. If this is a serious event such as a marathon, etc. This is something that their trainer should also have adressed. You never do an event such as this with new sneakers and you need the proper socks so that you don't get the friction that will occur. A friend of mine actually got blisters along her bra line from her arms chafing her sides!!! eek!!!