15 week old suddenly frequent dirty nappies

[ClareSleepy]

My 15 week old is formula fed. She used to have a dirty nappy every 2-3 days and in the past five days has suddenly started having two dirty nappies a day. She isn't having any more milk than usual. How many dirty nappies a day is usual for formula fed babies? I'm just wondering as this isn't the norm for her.

Mine use to go 3/4 times a day sometimes more

Teething often gives looser movements and more dirty nappies. Ds was still bf at 15 wks but definitely started teething and had more dirty nappies as a consequence.