How tall are you. At 150 lbs. I'm guessing you are about 5'4". If so that may be about right. If you are taller start eating.
A video would be helpful but when one examines your statement concerning exactly when the pain happened one finds this "but I think that my form broke down under repeated reps and I started to look up. It wasn't a shooting pain I felt, but more of a strong throb on both sides but stronger on the left. It went up the back of my head to the crown of my head, again, on both sides but stronger on the left."
First, what do you mean by "repeated reps"? After two years are you after LP? What program are you using? Are you carefully following it? If repeated reps means 3 x 5 that might mean one think. If it's 5 x 20 it would mean something entirely? How must rest between reps?
Second, when were you instructed to "look up" when doing the squat? This is not indicated in any Starting Strength literature. Never look up when doing squats.
Third, are you lifting at the extreme of your ability? If so, you may need to back off.
Finally, how many times do you confer with a certified SS coach? A certified coach could analyze your problem rather quickly and get you back on the right path. I'm with a coach twice per week.
BTW Are you male or female?