3D sketch drawings

Something happened over the weekend. I have been using 3D sketch for a number of thing and this is the first time I have ever had this problem. When i draw my first line i go to the next weither it be perpandicular to the end point, or on a different axis. I used to just draw the line which ever way i wanted it to go and then dimension it with no problems. now when i dimension it it moves the whole sketch. even moves from the starting point. why does it do that, i was wondering if i had changed a setting somewhere. i need to find out because it's a pain in the ass. Thanks