It seems that sometimes I live with a problem for quite awhile before it occurs to me to try to deal with it. It especially happens in regards to health issues. I think that is because I have so many things going on that I hope some of them will just go away. I know there are times that the first time I say something to my husband about an issue is two or more weeks after it started. He is very patient with me, but I don't want to over-burden him with my issues.
NOTE- The following should be viewed as suggestion, not as medical advice. Use your best judgment, and follow your doctor's instructions.
So how can you tell if a pain or other issue is worth pursuing? If it is new and severe, or disrupts your ability to function, seek help right away. If it is a symptom you have been told to watch out for, follow your doctor's instructions (eg- if he said call me right away, do that). If you have a change in medication, hold on to the insert that comes with the med., and watch for any of the symptoms listed for allergic reactions, and follow instructions. If you are unsure what you should do, (stop the med, go to the emergency room, etc), call your doctor right away. Anything that feels life threatening, of course call '911' or get to the emergency room.
If you have a new pain or other symptom that is not severe, take note of it, and see what it does over the next week or two. If it gets worse, go to your doctor. If it seems to be getting better, let it run its course. If it stays the same, use your judgment regarding how much it bothers you, and how important you think it is to your health. If it is a familiar symptom, either something that went away and came back, or showed up in a different body part, you are probably safe in treating it as you have treated it in the past. If it needed attention from a doctor in the past, it would likely need the same attention now.
Find a local or online community of people who share your particular malady(ies). I have found the Sjogren's Syndrome email list (SS-L@LISTSERV.ILLINOIS.EDU) to be invaluable as a resource for information on symptoms and treatments. Just remember that any online community should not take the place of personal medical care. It is a place for people to share their own experiences, which may not be the same as your experience, and knowledge, which may not be accurate.
This all boils down to learning what you can about your particular health issues, being attentive to changes, having a community you can consult, and, most important, using good judgment regarding how to care for your health.