I think it is good to be thinking about how our bodies are adjusting to ongoing colds and such. To be overly wrought about the potential for endocarditis is probably unnecessary. If anyone thinks they have had chest congestion, or sinus congestions for too long, a physician should be called in to assess. If we let a low level infection linger in our bodies too long, the infection can get to the diseased valve. There are many here who have had endocarditis, before and after surgery. I did not. I once had a long conversation with a woman who was very tired for a very long time, and whose husband (a psychiatrist) thought she was just depressed. Well, it turned out to have been endocarditis and she had emergency surgery and was very ill for a very long time. Because you lost your mother (I'm so sorry, by the way...just lost my dad for other reasons) over this infection, your "antennae" are out for yourself. This is good. You should honor each and every concern with a phone call to the doctor. You should insist that they be certain there is no infection. Antibiotics should not be abused. If you do not have an infection, you should not really use them for colds. We don't want to become desensitized to the medicines we may desperately need someday by using them randomly.
I do believe it is important to pre-medicate as others have mentioned, for certain types of procedures. I don't care if they do change the rules. I will always pre-medicate for the dentist and for colonoscopy and stomach things.
Nothing you can ask here will be silly. Nothing. Ask anything. That's what this community is for.
Work to lead a healthy life. Small infections should do you no harm if they are watched and you are resilient. Not every sinus or chest infection leads to endocarditis. It is the rare one, actually. Keep your dentist visits regular. Keep your teeth clean. That is one very healthy thing you can do.
Best wishes.
Marguerite