You really need to see a dentist in person as only they can give you a real opinion that matters. In addition, lots of gnarly things can accumulate under and near a crown & cause the very problems you speak of even if you take great care of your oral health.
Getting answers online might lead you to make a very bad choice and not have what is ACTUALLY going on seen by a professional that can help. People online are only guessing, even if they are well informed or are actual dentists. I highly recommend that for your own health that you visit a dentist.
If a lack of money is a concern, try visiting a dental school or a charity for discounted or even free services. They are not always available or convenient, but the health of your mouth and your overall health is at stake here and it is of the utmost importance. Best of luck to you.