Help baby vomiting everything out

Mo

He seems unbothered but is keeping nothing down. Not even breast milk. Have spelt flakes(for the first time) with banana this morning. Bought them n package said from 4 months. I don't know how to stop him from vomiting. He also seems not interested in any solids. Just breast milk. Which he vomits out too within minutes of consumption. My challenge is am running out of breast milk.n he is still hungry.