For A Month, I Have Had A Dull Aching Pain

For a month, I have had a dull aching pain on my right side under my rib cage. My doctor said it was most likely muscle related when I first consulted him but it has not relented and now I feel like it may be present on my left side. He is out of town for two weeks. Should I wait or be seen now? Any feedback on what the issue may be?