My daughter had loose stools and some tummy discomfort for about a week. When she strained to poop, sometimes the thick milk would also come out because she strained really hard. That’s just milk that’s been in the stomach for a while. Don’t think that’s a big issue as long as baby’s feeding well:)
Remember that the virus can remain in the poop for 10 days, so wash your hands well when you change the diapers:)