What are the causes for irritable crying? How to manage infants with irritable Crying?

A 3 day newborn presents with rectal bleeding. Discuss the causes and management .

6 months old baby with h/o fever with loose stool off and on 10 days.... Now abdominal distention for 2 days passing only slight blood and mucus... Please evaluate...

14-month-old male presented with a 3 day history of watery diarrhea that has progressively worsened and is now green, mucusy, with lab confirmed blood (small amounts seen in the last pictures). Patient otherwise fine until day 3 when he developed fever 101.5 max. Diarrhea occurs about every 1-2 hours. No abdominal pain/nausea/vomiting. Decreased appetite but drinking fluids (water, mom still breastfeed, and also supplements with goat milk formula due to past suspected cows milk protein intolerance). No changes to diet except mom started to introduce formula milk and states baby has been eating eggs more regularly and used to have an egg intolerance which she thought he had outgrown. Stool cultures and allergy referral pending. Thoughts? Infectious or allergic?

DOL7 WITH HISTORY OF COW MILK INGESTION H/O LESION OVER FLEXURE AREA ON ADMISSION spo2 75% on air CRT =5 sec HR=200/min RR=68/min

6 months old baby brought to the OPD with complaints of redness and skin rashes over buttocks and posterior part of thigh as shown in pictures....wt would be the diagnosis and treatment ?