Welcome to healthcare Magic!
is a gory problem when recurrent. It seems there is complication in splenic blood supply due to local inflammation in pancreas
Also get a detailed ultrasound
of abdomen to rule out if he has a normal liver.
If the spleen is bleeding it is worthwhile that it be surgically resected.
He should get the prophylactic vaccine
for pneumococcus which is a very common infection after splenectomy
The drains should stay there till they are draining fluid out. The problem will persist for long, probably for life so you yourself can decide about the option of DLA.
I hope the advise would be informative and useful for you.