A 5-year-old female presents with palpable purpura over the buttocks, arthralgias, abdominal pain with diarrhoea with passage of blood per rectum. The patient also has the presence of proteinuria. What is the most probable diagnosis -
Henoch-Schonlein purpura

Henoch-Schonlein purpura also referred to as anaphylactoid purpura, is a small-vessel vasculitis characterized by palpable purpura (most commonly distributed over the buttocks and lower extremities), arthralgias, gastrointestinal signs and symptoms, and glomerulonephritis. Clinical features
It is seen pediatric patients having palpable purpura.
Most patients develop polyarthralgias in the absence of frank arthritis.
Gastrointestinal involvement is seen in almost 70% of pediatric patients. It is characterized by colicky abdominal pain usually associated with nausea, vomiting, diarrhea, or constipation and is frequently accompanied by the passage of blood and mucus per rectum; bowel intussusception may occur.
Renal involvement occurs in 10-50% of patients and is usually characterized by mild glomerulonephritis leading to proteinuria and microscopic hematuria, with red blood cell casts in the majority of patients; it usually resolves spontaneously without therapy. Rarely, a progressive glomerulonephritis will develop
Nephrotic syndrome
Nephritic syndrome
Henoch-Schonlein purpura
Thalassemia