In my opinion the the physical withdrawal should not be as bad. However the psychological desire to take the drug will take a long time.
I AM NOT A DOCTOR
How bad your withdrawal will be depends on whether your tolerance went up during those 4 days of relapse. If by the fourth day you felt you couldn't get the same high as you could the first day of your relapse or felt you needed more oxycodone to feel normal, then your withdrawal may be pretty moderate since you were clean for just two weeks. It takes a while for the brain to readjust back to a low level of tolerance to opiates, so once you relapse closely after getting clean you basically start off right where you ended.
To be able to answer your question more definitively I'd like to know more about those four days of relapse. My questions are how strong was your euphoria on day one of relapse? And, did you feel the same amount of euphoria on day four, or did you just take it to feel normal and to prevent withdrawal? Also, did you crave more oxycodone to feel that euphoria from day one? And lastly, on day four did you feel any slight withdrawal symptoms while on the 30mg? Answering these questions will help me determine whether you will experience severe, moderate, or mild withdrawal symptoms.
This will be more of a mental thing for you now. What are you planning on doing now to deal with the mental part?