If you are holding, Ice and morphine works too.

I use ice and aspirin, I can't afford street morphine.

serious backaches.

generally, painkillers and even Oxy doesn't help much with my body (and my siblings are the same), but low doses of ibuprofen and an occasional Jack n diet worked way better.

sandwich baggie, (slightly wet), freeze it (into the shape you want, so it'll fit better) and vola, an ice pack that can be used more easily to fit into that tight spot, on the shoulder / chest area. Might make it, the baggie somewhat hanging over your shoulder (into a hook shape (the washrag)), freeze it, and it should fit pretty well.

tolerate it.

Moist warm heating pad can help or Ice packs if it is less than 24 hours. If it persists, call your physician and see if they will prescribe a muscle relaxant.

That’s what usually helps me.

If not better see a doctor.
If a little better, go on line and YouTube for yoga stretches for chest muscle strain. Same moves you’d get going to physical therapy.

Tonight and tomorrow, ice the area. Yes, it feels like shit when you first put it on, but trust me, 20 minutes on and 20 minutes off fduring the first 24 hours after an injury will cut inflammation and dull pain. After that, use a heating pad.

Lidocaine pads are over the counter now. Read the instructions and follow them to the letter, you don't want to absorb enough of the stuff to affect your heart rhythm, but they can work quite well on all sorts of moderate pain and are safe if you follow instructions.*

I have some salve that's basically Ben-Gay with CBD and works better than either, alone. You can order CBD products through the mail as long as they're made from hemp, but you might not get them in time. It's good for sprains and strains if you don't mind stinking and would be good to keep around if you insist on moving heavy furniture.

As for oral stuff, if you can tolerate NSAIDs like Motrin or Aleve, you can alternate those with Tylenol in order to sleep at night. If you can't tolerate oral NSAIDs, try the SalonPas pads, they contain an anti inflammatory but it's absorbed through the skin and will bypass your digestive tract (I have IBS, too, it sucks), just follow those instructions, too.

*Worst I got was some mild dizziness when I spaced it, dizziness cleared within an hour after removing the patch. It was on one foot, so it had been on for a ridiculously long time.