So afraid for my babies!!! Anyone experienced this??

Lindsay
I am pregnant with fraternal twins. We went in for our ultrasound Wednesday of last week and I was at 22 weeks. We had a normal ultrasound and after it was over the ultrasound tech said that baby bs head was measuring in the 24th percentile and that he was measuring 10 days behind the 22 week mark. Baby a was measuring 6 days behind and measuring in the 37th percentile (they didn't seem concerned about baby a). We spoke to the doctor after he looked at all the measurements and he basically said he was confused and the measurements didn't make sense. He said he thinks the ultrasound tech has gotten the babies measurements swapped somewhere along the way. That last month baby b had the larger head and now baby a has the larger head. They only weigh 1 oz apart (15 and 16 ounces). I made the mistake of googling what could be wrong and came up with microcephally which has me so nervous I was physically sick yesterday!  We have another ultrasound with another doctor Tuesday to get a second opinion. Both babies are very active. Has anyone experienced this and if so what was the outcome?  Were there any other signs besides the smaller head?