It sounds like your going threw withdraws a bit. The pill you speak of I get for breakthrew pain. They are
oxycodone 15mg IR (Instant Release) The other pills that you were on are
OxyContin 20mg.
They are the same thing, same ingredients ones just long acting and the other is instant release acting. You would be taking 5mg less with each pill to since one is 15mg and other is 20mg.
If I were you I would probally just take one extra oxycodone 15mg tablet. Even though they say your not suppose to do that you should be ok. Just be prepared to take one less during the month. That one extra should help with your withdraw symptoms.
Shawn