You might want to check inside her ears to see if there is odor or discharge there as that can cause a bad odor in a dog.
If she lies down out in the yard where she urinates that odor can soak into the dog fur leaving her smelly.
If you have a male dog or if she plays with one he might be urinating on her to mark her as his.
A strong urine odor can be associated with urinary tract infection which is pretty common in pups and also with a vaginitis discharge. If she is constantly licking herself she might be cleaning away discharge from vaginitis, leaking urine, or urinary infection.
Anal gland odor is rather fishy smelling like spoiled fish.
Skin yeast infections can also give a dog an odd odor which some describe as being like dirty socks.
If her stitches are out and her spay surgery is all cleared up you might try washing her either in an antiseptic shampoo such as Malaseb, Chlorhexiderm, or Pyoben shampoo or a deodorizing shampoo to see if that resolves this.
If the odor comes back after bathing her then you should see your vet to check into it to determine if there is some incontinence going on or an infection.
Hope this helps you!