Can Medication For Back Pain Cause Bad Taste In Mouth?

I have a pump in my side for back pain that I have to get filled about every six month. The medicine id Dulaudid. I have been having problems such as bad taste in mouth and can't eat. It taste like I have been poisoned. Every time I go to the Gastro doctor he keeps saying it is the medicine from my pump. Could this be true? If so what do I do? I cannot go without it because of my back I have had 11 back surgeries. I don't want a subscription I'm just asking a question. I have gone for several tests such as; MRI, Cat Scans, X-Rays and nothing shows up.