Yep, I agree. Try going up to the next size. We tried cheaper brands with both kids, but ours are skinny and tall, so they just didn't fit as well as Huggies. If you compare one of each diaper, the name brand ones have a stretchier waist band all the way around, and that made a HUGE difference in fit on our kids.
You might try putting plastic pants (or "rubber" pants, as my mom calls them) in between the clothes and diaper to try to help contain the mess and not soil the clothes. I do that anytime my kids have diarreah (that doesn't look right, but I'm too lazy to check!!). Also, if it's REALLY bad, I double diaper with the cheapest brand I can find on the outside. Just a thought....
Good luck!
Jenn