stares cereal now LO is constantly spitting up

My LO is 23 weeks. We were given the ok by our peditrician to start oatmeal cereal. 2 tbs of cereal per every 2 tbs of breast milk. He gets it everyday at 10:30 but only eats a few mouthfuls then gets breastfeed. We have been doing this all week and he has been violently projectile vomiting after every meal after 10:30. He never did this before the cereal. Could it be related? He gets buried after every meal and tummy time for 15-20 after every meal also. Has anyone else had a similar issue?