M.P.
Strip!! I use hot water 1 tbs of rockin green detergent and a squirt of dawn let soak for an hour. Takes care of the worst diaper cream debackle that we have had. Rinse several times with hot water if possible too. If that doesn't help contact fuzzibunz and get new elastic.
Also contact fuzzibunz and they can help troubleshoot with you. I would suggest you strip because that is always their first answer for you to try.