Hip Dysplasia in Dogs

Question
Hello, I have a question regarding my mix breed (Lab/Boxer) 70 lbs dog:

About 3 weeks ago we noticed a slight limp in her step after laying down for prolonged periods of time, and after walking up steps, so we decided to take her to the vet.

She was disgnosed with a slight case of hip dysplacia and we were told that without treatment it would only become worse. They recommended a treatment that "worked in most dogs" and that was:
1. Glucosomine/Condtriton supplement dizzled over her food, for life
2. "CondroProtect" injections, 2 a week for 3 weeks
3. Anti-imflamatory (1 week supply)

We began to see improvement after the first 2 weeks but then all of the sudden 2 days ago she could not put ANY weight on the leg that she originally limped on, and now she just limps around on 3 legs. She is scheduled for a vet visit in 3 days, we called to see if we could get her in sooner but the vet told us that she may just be favoring the leg because it is sore from all the shots, and recommended just waiting 3 more days.

Is there anyway the shots could be making the area extra sensative or having a negative reaction with her? any way it could just be stiffness? I realize you cant give me direct answers without seeing the dog and probably having x-rays, but are there any common side affects with this treatment.

I have tried stretching the leg in different directions to see if she is in any noticeable pain with movement (as directed by the vet), but she doesnt seem to make any objections audibly or physically to it.

Answer
Humble apologies for the delayed response.  You may have been in to your vet already but I will answer as well.  Any injections can cause stiffness and inflammation, or in rare cases even infection.  Given the timing it is quite possible the injection is related to the lameness, however it is possible than an unrelated problem such as a bone break, ligament strain or patellar luxation could have happened.  If you have any questions presently please let me know.  Again my apologies.