First 1/2 IM done - Cramping

Ok, now that my first 1/2 IM is in the books can anyone give me some good info resources or suggestions on preventing the cramping I went through at the end of the bike and at the end of the run. I have never had quad cramping in training or other tris, I've had calf cramps but those faded months ago and have not returned.

Pre-race taper, hydration and eating were usual. I think I did a good job pacing the swim and bike. I consumed two 20oz. bottles of Infinit on the bike as well as on-course water and a Clifbar. The day was not too warm, maybe 80-85 deg max. In the last 2 miles on the bike I felt cramps coming but not too bad. On the run, the cramps went away by mile 2, pacing was good to the 1/2 mark, I had hopes of raising the pace after the turn but around mile 10 I started to crash. I alternated sport drink and water at each aide station (every mile). The next two aide stations I walked through and jogged to the end with bad cramps - ofcourse the last 200 yards no pain was felt and the excitement of finishing chased it all away. I've done some long bricks and never ran into this issue so your thoughts would be appreciated.