Can a vegetarian diet cause stomach aches while the body adjusts?

I cut out meat about a month ago and I've had stomach aches for the last week.  I'm sure I'm getting enough protein, and I've been following an alkaline diet since January.  Is my body adjusting, or is it maybe not related to my diet?  My family is trying to convince me that this diet is not healthy, but I've read a lot of books, and I'm being very careful about what I eat.  Maybe I'm missing something?