At 4 months of age, your baby might be going through a growth spurt (there’s one at week 18-20 if I remember it correctly). Little ones are usually crankier and clingier during a growth spurt because every new development, physical or mental, is a huge challenge for them. Things we grown ups take for granted can make them feel extremely uneasy.
I found ‘the wonder weeks’ a simple but informative website which covers the topics of the many mental and physical leaps in a baby’s early life.
Tons of discussions about growth spurts can also be found on Kellymom or La Leche League International (LLLI).
Your little one could be teething as well. Sometimes babies can be teething for a good few months before the budding little teeth surface.
Anyway, if your little fella is not ill or sick, what he needs right now is a lot of love and cuddles.
This is just a phase and these phases DO pass. My little one is only 2 months older but I forgot all about month 3 and 4 already.
So just hang in there and it will become better and better.