What Causes Lack Of Urination, Stomach Ache And Swelling In Feet?

My 85 year old Aunt just called me to report the following symptoms: Haven t urinated for about 1 1/2 days even though I have been drinking a lot of water. Had stomach pain this morning, but it seems to have subsided somewhat. Legs and feet don t look very swollen, but feel tight. Trying to keep them raised as much as possible. She called the doctor, but since it is Sunday, she gets a recording. She didn t want to leave a message because it says on the recording that Medicare doesn t cover it (I assume she will be charged for the telephone call), so she hung up. I m concerned it may be related to her heart. She doesn t want to go to the emergency room. Advice please.