Firstly, taake 1-2 tabs panadol for pain relief. Then please chech your nipple. Any white spot found? If yes. Maybe a bit blockage. Try use the soft towel to rub the nipple gently.Or use your nail scratch the nipple very very gentle. And squeeze the nipple see any milk can come .If yes, continue to squeeze the breast as usual if the flow return to normal then you can use the pump.
If the above measure stil not work maybe go to the "mother child health centre" or your doctor for investigation.
if your breast duct is stuck ,please do not use the pump again, you have to use your hand to express your milk. but before, you have to take a hot shower, and use the very hot towel and put onto your breast, after soften your breast, you have to do some massage and express your milk, (maybe you have to ask your husband to help you ).
but the most efficient way is let your baby suck , so when your baby will discharge from hospital, or can you ask the hospital and see if they can let you feed directly to your baby?
i think if you baby is now staying in public hosptial, there should be some lactation consultant , so you can ask for their help, they are willing to help you, don't go to the private clinic as not many doctors have the knowledge about this, they only will give you antibotic.