Back pain: Heart issue or spinal problem?

I’ve been scouring the internet for a while now trying to find anything similar to what I’m feeling, but I’m coming up empty (so maybe it’s not actually a big deal??). For a few months now, I’ve been feeling this clicking sensation right around my sternum whenever I take a deep breath and my ribcage expands. It mostly happens during the day; when I'm lying down, it pretty much disappears. It doesn't hurt, just feels incredibly annoying. I get the exact same clicking sensation if I pull my right shoulder back. Again, no pain, just clicking. This all started about three months ago, right after a nasty bout of the flu with a ton of coughing—did I mess something up during that? Sometimes it vanishes for a couple of days, then comes crawling back.
Does anyone actually know what this could be? (I am terrified of doctors!!!!!!) Is something broken? Is it serious? Should I be looking into surgery?
I don't know if it's even related, but I'm not particularly active, my back aches if I sit in one position for more than thirty minutes, I smoke about half a pack a day, and my diet is pretty much whatever.
Someone please tell me it's fine... I'm starting to freak out.

Look, you should probably just head to the doctor—I mean, we aren't exactly medical clairvoyants here, right?😉 The thing about these symptoms is that they could be absolutely nothing, or they could be something seriously sketchy. It’s hard to tell without an actual professional involved.
You’re likely going to have to run a few tests, but honestly, I’m hopeful everything turns out fine.

If things start feeling worse, you really don't have a choice—you'll just have to go see a physician. 😉

Not trying to start a whole new thread here, but I gotta ask—how long does it actually take for a broken rib to fully knit back together? Like, when can I finally get back into serious workouts and just live my life without constantly looking over my shoulder, terrified I’m gonna snap something again? I had surgery where they basically had to plate the entire length of the rib... it’s been over a year now. Sometimes I still feel this weird clicking sensation. And if I lift anything even slightly heavy or move the wrong way, I get this dull ache in my chest for a few days, almost like something shifted out of place... anyone else dealt with this kind of mess before?