What Are The Side Effects Caused Of Oxycodone And Morphine Taken Together?

hello, my name is lori. I am 51 years old and have been taking pain meds for about 6 years. I was taking oxycodone for about 8 months ( 4 30mg a day). Due to problems with my daughter trying to steal them, I chose to take methadone instead and I took it for about 8 months (85 mg daily) but I felt completely awful, so I Have been back on 4 30mg oxycodone a day plus 1 60mg morphine at bedtime. I started them back on Jan. 9th and it was ok at first but they just have not worked as well as they did before and since I got my prescription filled a couple of weeks ago I have been having headaches and food makes me nauseated. I am trying to eat. I felt that way when I was taking the methadone. I work a very physical job and I have taken more than I should so I can get my work done and now they hardly seem to be working. I feel awful. I went back to my dr. and he gave me a steroid shot and methylprednisolone pack. He also put me on Celebrex. I just feel so awful, I cant work like this and I m also getting custody of my 4 young grandchildren next week, What is wrong with me? Why is the pain medicine not working? Is there a different med I can try? This is so frustrating! Oh I take the meds for back and neck pain and arthritis. It is unbearable without it, so I guess it works some but not great anymore. Thank you