Why Is My Infant Vomiting Repeatedly An Hour After Dinner, With Milk, Food, Then Just Water And Froth, For The Second Time This Week?

Hi, my 7.5 months old has vomited after having dinner , almost an hr later. She ate some chapati bits and then had feed. At first she vomited all the milk n some food she was having , then she kept on vomiting after every 5 minutes. Later everytime she was just vomiting all water and some froth. She vomited almost 6 times. Also she had to put lot of pressure in vomiting but hardly some water was coming out. What s this . This has happened for 2nd time this week