Nine month old Chocolate lab limping, not eating much, limping, constantly drowsy

Question
Our eight/nine month old lab seems to always be tired through most of the day. She has her moments of hyperactivity, but it only seems to happen for an hour at most, until she is drowsy, mopey, and seemingly tired. Whenever she gets up in the mornings, I'll go to feed her, but she'll just ignore the food and get around to eating it in small portions throughout the day. She has been known to eat the catfood located on the other side of the kitchen on occaisions, but we've been trying to watch and control that, which has worked thus far. And last, she's been limping on the same paw lately, not all day, but every now and then. Although it's not a dramatic limp, it is noticeable when watched carefully. She also goes through various drowsy stages throughout the day. She can usually jump onto the sofa bed in my room with ease, but sometimes tried and plops her upper half on the bed, and struggles to get her two back feet up as if she was just too tired to put forth the effort. Am I just being a worry wart, or could something really be wrong?

Answer
This doesn't sound good at all.  Most, but not all Labs are highly food motivated unless over fed.  Over weight is a big problem, stressing developing joints.  Also, an early switch to adult chow slows growth, allowing more time to develop sturdy joints.  here is a link to a great guide to how much you should be feeding her, http://www.puppychow.com/products/popup_body_condition.aspx

The limp and lack of energy will take more than the feeding changes I suggested.  She really needs to be examined by a vet.  There are some problems that cause limps, but the dog grows out of it.  Yes, something may be wrong.