It may the uterus muscles contracts when you sneeze , there is no problem i think well m not a doctor ,, but you should go and get yourself checked.
I would go see your doctor. I had lower abdominal pain for years while in college. I would end up in the ER and they would try to tell me I had an STD. Always tested negative for those and then they would give me a shot of something and send me on my way. When I was out of college the same thing started again and I ended up with some other problems. It may just be your fibroids though. I had those when I was pregnant (not saying you are pregnant) but the pain was very much like yours. Your gyne will be able to check and do and ultrasound and exam. Checking for a hernia is also a good idea. Good luck to you! =)