What Are The Long Term Effects Of Taking Oxycodone?

I have been taking Oxycodone for 15 years. 15 mg 4 to 6 times a day. For some reason they stopped working as well during the day and I wake up with pain so bad it sometimes takes me over an hr to get out of bed. I have also noticed almost time I fill my RX the pills are made from a different company and with some research I have found that they were made out of the country. Tolerance? or medication not even close to FDA standards? I have never been in so much pain in years and now they stopped working like they have for years. Please help.