L.M.
Definately time to switch.
For both my daughters I only used Dreft for the first 2 months. I use All Free and Clear. My youngest has eczema and the detergent has no effect on the eczema.
If you're using a heavy duty detergent like Tide (both my daughter and I are allergic to it), only wash a few articles at first and look for any type of reaction before completely switching over.