What Can Cause Odd Smells After Bilateral Knee Replacement?

I am about two weeks post op for bilateral knee replacements. All has gone well with the knees. However, I had neped the pain meds on 11/13/10, am feeling a little better. However, I have developed a pervasive sense of smelling plastic or burned plastic. It colors my taste as well. Is this due to medications, surgery, the implants, or something more closely related to my emotional/mental/chemical imbalances?gative reactions to the pain medications (hydrocodone and oxycodone) as they interacted with the antidepressant Welbutrin and Methylphenidate. I stop