Hi,
Compeed is the worst thing you could do on large blisters. Beware of that!
Either, when you continue walking, you will tear the skin off your feet when taking off your socks. Or you will suffer a severe infection (blood poisoning) as Compeed not only seals the blister but also the bacteria in it and while you leave Compeed on your feet you do not see how the infection develops.
An experienced hospitalero or a nurse can help you to treat bigger blisters. They open it with a sterile injection needle (which you can buy in a Pharmacy), let the water flow out and inject some "betadine" (desinfectant, Iodid) instead, cover the blister loosely with gaze and let it dry overnight.
Best is to prevent blisters. When you feel, that some part of your shoe is rubbing on your skin, stop immediately and cover the skin with "tape" ( e. g. Leukotape, textile and a bit flexible - not the grey plastic stuff you see on the photo above).
BC
Alexandra