Inhaled water in bath

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My son and I were practicing blowing bubbles in the bath (he's 20 months). He of course inhaled water. He coughed and a bunch of water came out. Coughed again and threw up. I brought him out. He continued to cough off and on for a few minutes. He seems fine now but I get so afraid of dry and secondary drowning! Keeping him up a little later to watch him. What would you do?