If you or the person you care for is in a life-threatening situation, dial 999 straight away.
If the situation is not life-threatening, contact your GP or hospital liaison, where possible. They will have a better understanding of your past medical history and should be able to advise upon any new symptoms. If this is not feasible (out-of-hours or this would take too long), dial 111 to speak to NHS staff, who can advise you on what to do next.