Do you mean 'i developed a pain in my abdomen, when i had a wet dream'? sorry just wanted to double check :) It's possible you may have overstretched your muscle while you were asleep. Apart from that, it would be very unusual to have pain in the abdomen as a result of having a wet dream. were you doing any physical activity or sport on the day/night you had a wet dream?
tell your mother about it... wet dreams are normal. so dont be shy about telling her for that.. they happen to everyone. at a certain point in life. and shes your mom, its her right to know about it and not care even with the most embarrassing things... just dont think about it and tell her.. goodluck :)