What Causes Severe Joint Pain Causing Inability To Move?

I have been taking Pristique for 4 years, recently my Dr. Upped my daily dosage from 50 mg to 100 mg. I sat armed with severe joint pain I cannot lift my left arm without severe pain. While grocery shopping I cannot bend down to get a food item on the lower shelf! I am a 54 year old woman and wondered if the increase of Pristique could be the cause.