Normal post operative pain can last as long as three months. It is very unusual to have pain this long but it does not mean that anything has gone wrong. There are exceptions to this and it takes qualified medical judgement to make the determination.
In my practice most patients are off pain meds within 3 or 4 days. An occassional patient can have pain for longer with no apparent reason. Bad bruising can cause pain that persists for weeks.
A mesh complication can create symptoms starting the day of surgery but making this diagnosis early is extremely difficult. In nearly all cases we simply wait for at least 3 months. You should be in very close and careful follow up with your surgeon during the entire time that you have pain.
Many of the patients that I do mesh removal for knew immediately after mesh hernia surgery that something was wrong. There are cases where I believe immediate removal of mesh is justified.