Can someone please help me find this.

It's one where Sesshoumaru is turned into a baby. Either the group finds him or Rin comes to them for help, I can't remember which. The only other thing I can remember is that Kagome is going to take baby Sess for a bath and Inuyasha throws a fit.

I think what your looking for is this
Chibi Fluff rated M

Sesshomaru is turned into a little kid again when he denies to mate with the Eastern Demon Lord's daughter, the reason he would not mate with her is because he was already in love with someone. Can Kagome help him? Sesshy OOC SesshyKags

So far the story only has two chapters out and if that was what your looking for might I suggest this story
Puppy Love it's rated T

Sesshoumaru decides to join Inuyasha and his group in order to defeat Naraku… much to Inuyasha's displeasure. Unfortunately while fighting one of Naraku's new reincarnations, Sesshoumaru is changed into a kid again! Now Kagome has to take care of him...

I personally love it and think it's hilarious, i hope i was a help to you

Thank you for the help but this isn't the story I'm looking for. I did enjoy reading Puppy Love though!

Are you sure it's not Chibi Fluff, the end to the second chapter has Kagome taking little Sessh to the bath and Inuyasha making a fuss, hmmm are there any more details you remember to the story?