What nutritious foods and snacks can I substitute for dairy?

I'm trying to lose weight and everyone always tells me to have yogurt as a snack or drink a glass of milk a day. I don't like milk, so unless it's on my cereal or as a topping, I won't drink it. Furthermore, I am very sensitive to dairy products. Some dairy products I eat or drink make me cough a lot and feel like my throat is closing up, other dairy products don't make me feel that way at all. I'm not sure if it's the content- some products have more dairy than others - or what. I would love to be able to have yogurt as a midday snack but it seems to be the worst. I haven't tried a yogurt yet that hasn't made me feel like my throat is closing up/lots of mucus- thus the continuous coughing. Is there anything I can substitute?