breastfeeding and congestion in baby

Just wondering if anyone is experiencing this. My 2 month old seems to constantly be congested I have tried everything! I eat pretty much everything and am rather healthy. I do have dairy products. Yogurt, milk, sometimes cheese. This past week I probably had more than usual and baby's poop was different than usual, diharea and more frequent poops today. I exclusively breastfeed and wondering if anyone has had same problem with dairy intolerance and congestion being a sign? Thank you!