I usually wait for the mud to dry off, ( I got a paints and white horses lol so im used to this ;) EVERYDAY ! )
So anyways, Do that and than Groom HIM ALL OUT With Lots of Elbow grease lol, use the curry comb first.
It Certainly Gives an Improvement !
In fact, I can show you what MARSHMELLOW LOOKS before and after :)
I would wait for him to dry and brush the mud off with a stiff brush...the rain may help to get him a little cleaner too. Perhaps a bottle of Miracle Groom would also help for the more stubborn stains. I use that on my Paint in the winter when he gets too dirty and bathing isnt an option.
I am glad that he is feeling better , colic can be kinda scarey IMO ....gotta love those Paints : )