Tremors in toddlers

Our 18 month old granddaughter is walking 3-4 steps unassisted but seems to throw one leg out a little too far to the side and loses balance.  She doesn't say recognition words consistently but will point to mommy, daddy, sister, and objects in a book when asked,"Where is...".  We are concerned about developmental delays, but our greatest concern is that she displays tremors in her arms and legs  when walking, even with adult support, climbing stairs or with any physical exertion.  Should we be concerned?  What could cause this? What should be ruled out? What can we do to help?