Patient instructed Signs that your pacemaker isn't working as it should or you have developed an infection or blood clot include breathlessness, dizziness, fainting, prolonged weakness. A swollen arm on the side of the pacemaker.chest pains.prolonged hiccups.a high temperature of 38C or above. Patient instructed Tell your doctor if you gain weight, if your legs or ankles get puffy, or if you faint or get dizzy.