Can someone give me knowledge of this for a four month old. My baby daughter chokes a lot on spit.…

Can someone give me knowledge of this for a four month old. My baby daughter chokes a lot on spit. Sometimes milk or other fluids. Is this normal for a them around this age. I had a scare tonight that she had problems breathing. I called the emergency peeps because I was so scared and worried. One minute she is laughing and next she coughs. And is gasping and moving her legs around constantly. I pick her up and pat her on back. Before this her nose was runny. When she was done and breathing on her own her eyes were slightly red around and again she was breathing but her legs started turning purple. With red blotches. Maybe lack of oxygen to her legs. ?? From choking. Is this normal? And what am o to do. She has a doc appointment Tommorow. She is good and dandy now. When they showed up she went back to normal quickly. I was in tears and crying cause I felt like o was gonna loose her for a brief second. Anyone have this experience. Thoughts advice some encouragement?!