Pain meds are getting less effective. Should I increase?

I am 18 years old and am being treated for Hodgkin's Lymphoma. I have knee, shoulder, and arm pains. I was on oxycodone 5mg and I took 2 every 4 hours as needed. This was giving me breakthrough pain so they switched me to oxycontin 10mg twice daily. I have been taking this fr about a week and a half now. For the first few days, with the exception of a little breakthrough pain, this seemed to be working well for me. However, it seems like over the last few days this has been less effective. Now I would rate my pain at a 5 out of 10 on average. At least a 7 out of 10 when I have breakthrough pain. I am having trouble sleeping because of this. I am achey all over. Do you think it's because I have developed a tolerance or because my pain is getting worse? The thing that worries me is that the doctor doesn't know why I'm experiencing pain in the first place. He though it might be because of the dexamethasone I was on, but I got weaned of and haven't had any of it for over a week now and my pain seems to have gotten worse. Hopefully my doctor doesn't think I'm trying to con pain meds. My biggest scare is being labeled an addict and made to live in pain. It scares the hell out of me and I feel bad for the people who have to deal with chronic pain and get accused of being drug addicts. It's terrible. Any advice?