I only inject into gluts and shoulder. I get these lump/knots where I inject and it does go away if I avoid that site but is that something that I should be concerned with or what can I do so I don't get them. I try and rub the hell out of the spots but it doesn't go away.
Scar tissue makes injections more difficult over time.
Start rotating site injections as 4thAD said.
You want your muscle tissue to be smooth and pliable, not stiff and lumpy.
Deep tissue massage helps.
DIV