Temporary lactose intolerance after a stomach virus?

Hey, my baby is still suffering from an anal fissure :-( The stupid fissure was almost healed, and then he got diarrhea from a norovirus. Then there was a few days of relief, the fissure got better again, and now he constantly has gas and diarrhea :-( The fissure has reopened... I've now bought him lactose-free formula (Neocate) because I read that a virus can cause temporary lactose intolerance. Has anyone else had a similar experience?

Best regards, Raffi