Congratulations on the new baby!
Nursing from both breasts is normal, so is single-side nursing. And so is combination of both (which is what my daughter does now). Growth spurts always change things, so perhaps that's what was going on.
When we had colic, Gripe Water (alcohol-free) and Boiron Colic Remedy (homeopathic) were helpful. But really the best thing was my sling - talk about a life-saver!
All the best,
Mellissa