my 6 month old son cries/ screams inconsolably at night around 11.30 pm 12.00 for 10 min weakly once?

my son since the age of 2 months(he's now 6 months) gets up at night cries with tears for 5-10 min then goes off to sleep. its a fearful screaming cry . earlier it used to happen once in fifteen days but now when he's 6 months its occuring almost once every week . he cries inconsolabaly for 10 min with tears . wont accept milk at that time. he's breast fed but now we ve started giving him cerelac n mashed rice.. smtimes we feel he has had a bad dream but recently we were more concernced as it happening once every week...please help if u ve any solutions