Any advice?

My gal Mouse, has an odd growth on the side of her neck , you have to part her fur to find it, it's very small, about the circumference of an eraser, once and awhile you can squeeze it and something cream colored squirts out, she doesn't show any pain or seem to know it's even there. Is this something to be worried about?

In my opinion any growth should be looked at by a vet, especially if it has been there for awhile.  Chances are it is probably a cyst, like a pimple, but what if on the off chance it is something worse, it is best to get it checked sooner then later.