What could be wrong if you have a sharp back pain on the inside of the left shouder blade close to the center and it hurts when you breathe deeply and perform simple tasks like reaching for something?
You most likely have an inflamed, hernaited, or ruptured disc in your neck! i know from experience, treatment is rehab or surgery and rehab but i had surgery and rehab... it depends on how bad you have injured it.
It sounds like it may be a form of inflammation of the muscle surrounding your shoulder or perhaps even the tendons are inflammed in your shoulder and the surrounding area. I don't think its serious but I'm not a doctor so see your own doctor for a examination.
It could also be a classic case of a rib subluxation. A subluxation is a misalignment of a joint that is less than a dislocation, but still lacking proper articulation. All 12 ribs have joint attachments on the vertebrae, or spinal bones.
Your rib cage expands everytime your lungs expand. So if there is a rib joint that is out of place, then you'll feel it everytime your ribcage significantly expands.
Reaching for something can definitely aggrivate the area. You are asking the body to fullfill a full range of motion, even when there is disfunctional movement in a specific joint. The contracting muscles that surround the misaligned rib are still forcing movement in that area.
The solution is to see a chiropractor. A chiropractor can adjust the rib back to where it needs to be.
The MOST LIKELY answer is one of the following:
A. A muscle spasm... You probably injured the muscle while lifting something fairly heavy and turning/twisting at the same time. Injured muscles -- and the muscles around them -- spasm or cramp, trying to immobilize the injured area... kinda like a splint on a sprain or broken bone. It's a protective mechanism...
What do do about it? Well... a lot of my patients had this, as well as myself, and it sure isn't much fun. If you know when you injure yourself, use ice on the area for 20-30 minutes initially to help reduce the extent of deep bruising. Then applying heat several times a day for 20-30 minutes each time can increase circulation in the area and help speed up healing. If you seem to have a lot of problems with this kind of problem [like I do] do what I did...I personally bought a hand-held massager at WalMart made by Homedic. It's about $35. It has two rotating heads that massage deep into the muscle; in addition, there are several 'heads' that vary the kind of massaging. It even has a couple of heads that you screw on that allow them to heat up, providing deep heating to the injured muscles. These massagers are so comforting, we keep a couple of them around, just in case one quits working [they are quite reliable]...
Another thought... Some people respond to ice over heat --and vice versa-- so after you've tried both, stick with what seems to work better...
It's doubtful that bengay or Aspercreme can penetrate deep enough to the damaged muscles to be of much value, but it certainly doesn't hurt to try them...
B. The other concern could be that you have pleuracy, or inflammation of the linings between the lung and the chest wall. Feels like someone stabbing you with an ice pick!! OUCH!! Inflammation leads to adhesions sticking the two linings together [picture pushing a plastic trash bag into a trash can... one wall of the bag is next to your hand and the other is next to the trash can wall... A deep breath pulls at the two walls of stuck-together pleura, causing the pain... Usually caused by a viral infection [chest cold]. Usually goes away in a couple of days.
Please note: You should see your doctor and put your mind to rest. The above answers were good ones and I'd like to add even the way you sleep at night can cause this. I've had the same thing, went to the doctor and I had a muscle spasm. Still, ALWAYS see your doctor when these types of things persist.