I am 29 weeks pregnant and have been having a lot of pressure in my pelvic area for 3 or 4 days with a dull back pain I went to the dr and he checked for dialation I wasn't but what else could this mean

It is pretty normal for some women. As the baby is growing all of your internal organs are getting squished up.

If he felt no concern, then let that alone ease your mind. This is normal and intensifies (usually) with every pregnancy after your first.