Shell Script to Execute Shell Script to All Subdirectories

I am making a script to simplify my daily tasks. Everyday, I have to grep for a few things inside a company server. It was okay, however, now, they have segregated each object into sub directories. I am looking for a solution in which my existing shell script will execute repeatedly into each sub directory inside a certain directory. How do I do this? I am quite new to Linux and still learning the ropes.

Here's my script:

#!/bin/bash
MainDir=/path/to/dir/containing/subdirs
# cd into dir
cd $MainDir

for dir in $(ls); do

#fetch start time of uut
grep -i "01_node_setup" $dir/his_file | tail -1 >> /home/xtee/sst-logs.out

#check if sysconfig.out exists
if [ -f $dir/sysconfig.out];
then
    grep -A 1 "Drive Model" $dir/sysconfig.out | tail -1 >> /home/xtee/sst-logs.out
else
    grep -m 1 "Pair0 DIMM0" $dir/node0/trans_file_prev/*setupsys* | tail -1 >> /home/xtee/sst-logs.out
fi

done

#cd back to where we started
cd $OLDPWD

A nice guy helped me with the script, and the script above is what came out. It worked alright however, the sst-logs.out file displays binary file /some/subdirectory/ instead of the output of the grep. What is wrong in the script?