You've touched on a good topic. I have fibro and lupus. For me, the fibro did seem to come on very suddenly. I had my diagnosis of lupus first, and then about 4 months later, the fibro dx came. Like you are experiencing, I had a lot of soft tissue pain. Just the slightest bump, or poke KILLS!!!! It's like I am one huge bruise. My arms, thighs, and ribs are the worst for pain if I get poked or bumped into.
Often, fibro and lupus are so much alike that it's really difficult to determine what is flaring. They present almost the exact same symptoms of pain, fatigue, etc. For me, the only way to know if it's fibro is if I increase my prednisone, and I feel worse, then it's fibro. If I increase my prednisone and I feel better, then it was lupus. Fibro and prednisone don't like each other. Fibro isn't an inflammatory disorder. So prednisone doesn't work on helping it. It makes it worse actually. Are you on prednisone?
Your symptoms certainly could be fibro. The only way to know is to see your rheumy about it. They'll do a pressure point test and record your symptoms. There is no blood test for it, unfortunately. Fibro IS horrible!! I loathe it...... It almost gives me more problems than my lupus most of time.
I sure hope you get some answers. A warm or hot bath is always a good idea if you're in quite a bit of discomfort. Baths really help me.