I have had stomach pain on and off for three weeks. I also feel nauseous but no vomiting. Also I have been having headaches. I went to see a doctor and he told me I was congested and prescribed me a decongestant. I felt much better last week, but on Monday my symptoms returned. Today my stomach is very painful, and I feel nauseous. Also my lower left back has a sharp pain when I move. Do you think I should go to the emergency room?