I have a 48 hour rule. IF the new or worsening sx last more than 48 hours and I cannot find an explaination (Like a cold) for them then I call. But I also know that 9 times out of 10 there is nothi they can do for it. So I leave a note with the nurse...who leaves a note for the doc so that it goes in my file. If it is something that can be treated the doc will call me and ask if I want to try (Insert Random Medication here).
Most of the time, it is handled by phone with either the nurse or the doc. But there have been a few times where the doc has called and said "I need to see you!". But she also knows I am not a fan of conventional medicine, and I hate taking pills. So she knows that I will not take them unless it is really bad.
WOW that was a little long winded simple answer: if it lasts more than a day call your doc.