What is a painful spasm?

The muscle more commonly involved in neck spasm is trapezius, which is located in the mid line just above your shoulder blade. For more details regarding this search for "trapezitis" in Google...

Angina

Synonyms for spasm: pang, pain, stitch, ache wrench, cramp, stab

Although it can cause pain and discomfort (as well as bleeding and problems passing feces) in some cases, it generally is not a painful condition. In fact, in often it doesn't present any noticeable...

The level of pain varies among women, and surpisingly enough, is not necessarily related to how bad the endo is (i.e. the extent or size of the growths). The pain can be described as "killer cramps"...