My son is 21 days old, and he appears to have discomfort in his stomach. every time his stomach makes a grumbling sound he stretches his legs and sometimes curled them up. he also suffers from hiccups. this discomfort affects his sleep and he cries?

Pretty common: At 3 wks the average normal kid fusses about 2 hrs a day for no reason. They also lears to cry to be fed or be picked up when lonely.They generate the power to fuss from their breathing muscle which pushes the belly out. They all have grumbling sounds of the air they swallow in their tummy. Hiccups are common starting before delivery. This sound pretty routine. I wouldn't lose sleep over it.