Breastfeeding when ill. I need help

Courtney

Me and 12 week old baby have had gastroenteritis and just getting over it and my right breast is very engorged, I expressed 5 ounces and nothing has changed, I don’t know what to do she’ll only feed off that breast a couple of minutes then cry. It’s usually her preferred breast and she has fed quite a bit off it but I’m unsure what to do should I express again?