10/20 super deep(Avg stacks 400bb..fish has 650bb,I cover him)

Fish is random,spazzy..mostly overlimps entire range if it is a limped pot...but 3-bets very wide if someone has raised.I have seen him overlimping very wide as well as strong hands such as AQ,KQ,JTss(some hands on showdown).Villain is playing 75% of the hands.

FIsh also likes to barrel a lot.if he has taken the lead.

i limp mp w/ 4d4c

fish limps..btn makes it 100$ .SB & BB call.Me & fish also calls.

5 way to the flop (500$)

Flop : 8c4s5c

Sb(tight reg) donk leads for 400$..BB folds.. I flat ..Fish makes it 1900 $

Everyone folds..action on me..

ACTION ?? & THT PROCESS??

ALSO WHT DO I DO WITH 88 & 55??