I have a bad habit of holding my feelings in because my family will just say "She just wants attention" or "Suck it up" "Stop crying" "Your not a baby" so I grew up keeping it in and acting happy so when I'm on the edge of crying I hit my head to stop myself from crying unless I'm alone.
But no matter what you have to let it out even if it's alone holding it in will not help in the end. Have a blessed day.