My sister is having trouble getting her son (about 4-months-old) to stop crying! I've tried suggesting a few different ways to help her out (that worked on my daughter when she was the same age) but none of them seemed to work. Does anyone have any tips and tricks that I could possibly forward to her?

Usually at 4 months, babies cry when they're sleepy, hungry, wet, or not feeling well. So if feeding, changing their diaper, or soothing him doesn't work, there may be some discomfort that he can't verbalize. It's best to consult a pedia because babies usually calm down when rocked to sleep, changed, or fed. Hope this helps!