See these 2 are very different things that ur baby is not sucking properly or less milk produced by you...if baby is not sucking properly and if he or she is become very dull and its movement are decreases then there is a chance of infection called as septicemia to ur child...if he or she is nrml but problem is ur with milk u can press the nipple and can see wheter there is appropriate milk is coming or not...
Next Steps
For both treatment is different...if there is less milk is producing there is a Shatavari granules available in market take 2tsp with milk..and Tab Leptidine is also available..consult ur doctor over there and take these medicine it will surely help u to increase ur lactation..