Chest Pains, Back Pains, PLEASE HELP with some insight...

[IGKiLLaBeeIV]

I'm 37yrs old in good health, I do not have a car at the moment so a bicycle was my means of transportation ti'll it broke last week... So now I'm forced to walk everywhere & this includes when i need to go fpod shopping. So 5days ago I went food shopping at a store 5miles away "the day my bike broke I was on my way there" So I had to walk back home 5mi with a backpack that weighed prob 50lbs, the next day I woke up in EXTREME PAIN in my chest when breathing in or out, when taking a deep breath my whole chest area feels like it tightens up, anytime I bend over "forward" the pain in my chest is absolutely unbearable it forces me to have to stand back up, I'm also no longer able to lay on my left side when trying to go to sleep. Also it seems like if I try n mess with it, by getting a back massage or rolling on a tennis ball it seems as if it only makes it worse. I'm not new to back pain n things of that sort, usually it's a knot or pinched nerve but this is different, this is way different... Not sure exactly how or what to do & I really would like to avoid the ER at all costs. Any help would be greatly appreciated. Thanx 4 taking the time to read & respond if you happen to respond