I have severe pain in my left deltoid muscle. This has been hurting for several months now, but the pain is becoming worse. To my knowledge, I did not injure it. If I run my hand over the muscle it feels like there is a lump. I have great difficulty reaching toward my back, like to unsnap my bra and reaching high over my head. If I roll over on my left side at night, the pain is bad enough that it wakes me up. Otherwise, I am a healthy, white female, age 55.