Re: two lumps in trapezius muscle?
Sounds like trigger points. They are very common, especially in the upper trapezius. And with your history of neck injuries and back pain, you are particularly likely to get them.
I've had trigger points for a good many years now. I manage them through stretching, weight lifting, gentle massage, heat and ice. They aren't dangerous, but they are associated with painful sore muscles.
Look up trigger points, and let me know if you have more questions.