I completely agree with Red's assessment of the situation. Especially since there is some swelling there. If it turns out to be a minor sprain, great! But it's best to get it checked out now, because if there does turn out to be a mass involved, it can be removed early on to facilitate a speedy recovery or, heaven forbid, in the event it could be malignant, give the animal the best chance of being able to be cancer-free. I know I'm really jumping the gun here, but with a senior dog, which an eight year old shepherd definitely is, you can never be too careful.
Please let us know what happens.
Ghilly
You should not wait to get it checked out. When things like this happen it could be something that is much more serious than a sprain. If the dog is limping on it then there is some pain there. If there is a tumor there it is best to catch it right away so that it can be addressed.
A sprain would be a good thing in this situation.
Please take the dog in to be checked out.
Let us know how you make out.