Here is a short (and far from complete) list of possible answers.

Usually, a baby can be soothed by addressing one of the big 4:

1. ​Hungry
2. Tired
3. Dirty Diaper
4. Gas

Sometimes there is something else going on:

5. Diaper rash
6. Too hot
7. Too cold
8. Loud noise
9. Too quiet
10. Wants to suck
11. Wants to be held/feels alone
12. Hair wrapped around a finger or toe
13. Fever
14. Teething
15. Overstimulation
16. Clothing tag/velcro from swaddle is rubbing skin
17. Swinging, but wants bouncing
18. Bouncing, but wants swinging
19. Reflux/silent reflux
20. Pain from recent heel pricks, vaccinations, other medical interventions

Looking at this list may make you want to laugh or cry (or laugh-cry simultaneously).  But remember, an infant’s cry is a reflex, not an emotional statement.  Make your baby as safe and comfortable as you are able to, and don’t be afraid to ask for help when you need it. We are here for you!