Nagging muscle ache in shoulder

I don't know what I did, but off and on the last 2 weeks, I've had this nagging ache under my left shoulder blade. It's as though I pulled something or slept wrong. I'm right-handed, so it doesn't seem feasible I'd have lifted something heavy with my left arm/had, but I can't remember. It doesn't so much hurt as it just feels annoyingly "not right". And makes me reach around to massage it often.

When I take an Advil, it goes away for a day or so. But this morning, it's back. Not so fierce as it was at first, but still, well...annoying.

I'm thinking deep muscle tear, or something? I don't think I should be worried, and I think my doctor would just tell me to take Advil and tough it out; but what a body part to have act up just now.  And what could be causing this?

Are you drinking enough water? It could be lactic acid building up in your muscles.  You can try eating bananas...that sometimes helps.

Have you tried massage therapy?

Good thinking. I know I don't drink enough water. Maybe that's part of the problem. I try to remember, but I forget. I think a massage would hurt me right now, though. I'll try upping my water intake for now.  Thanks guys and dolls.

Oh yeah. do you think lack of potassium has something to do with it, too. I know that's what bananas give you. I love them, just haven't had any in the house for awhile. They're so expensive lately.

Oh yeah. do you think lack of potassium has something to do with it, too. I know that's what bananas give you. I love them, just haven't had any in the house for awhile. They're so expensive lately.

Yes it can be..sports therapists recommend it for muscle aches.
ETA: Also good for lady pains 

Wow, I never knew that. Thanks bunches. I'll have to make a grocery run.

Go to the doctor, if he tells you to take ibuprofen then that's that.

But I've been having pain in the knee, doctor said it's probably muscular but sent me for a precautionary x-ray, that didn't show anything up so now sending me for physio.

Thanks bunches.

Of bananas! 

You should get checked out by the doctor too.

"of bananas" I made a funny and didn't even realize it! 

Thanks. I'll give my doc a call. May as well have one last check up before I leave for UK anyhoo.