Yeah, rest.. rest.. and more rest!
Stoumach muscles are some of the hardest to rest properly, because you use all your abdominals (external, internal etc.) CONSTANTLY. You will seriously need to rest like crazy, and DONT use painkillers, because then it will take longer to stop it because you wont know when the ache has naturally gone away. Its the same with most muscular aches really.
Another good thing is plenty of protein, and as you want your body to release it slowly over time, start your day with one with MILK! Water allows it to absorb very quickly, milk does it slower apparently. So yeah, protein with milk. Muscular aches and injuries always need some easily absorbed protein to get them to repair. Make sure you get some complex carbs too, otherwise that protein will be useless.
Also, if you do pushing hands, DONT until your abdominals are better. Even relaxed they will get put through a lot of exertion. I did pushing hands for several hours once, and ended up out of action for almost a week
. But it was WORTH IT!
Also, use jow if you'd like, but you still need to be able to feel the pain naturally, so that you know when it has naturally gone. If you dont do that, then as you use the muscles because you cant FEEL the pain, you end up making it worse, and last longer.
Hope that helps!
Also, if its a serious stoumach pain that hasnt come from exercise, take yourself to a doctor. Its not worth getting a hernia!