If you could tell me more about your pain that'd be great eg. whether the pain is in the centre or it is spreading to left/right side, since when has the pain started, did you lift anything heavy before the pain?
Next Steps
If the pain is severe, my suggestion would be to lie down on one side (left or right... whichever side you are comfortable), fold both your knees and lie down in that position for 48 hours. No sitting/standing/walking. Get up only for using the washroom and eating.
If you are not allergic to it, you may take Tab Ace Proxyvon (1 tablet twice a day for 3 days). Also, apply ice 5-6 times a day.