Swing Low, Sweet...Nope. Nothing sweet about lows!

Ok, lows are not my friend. Joshua has been consistently low for more than a week. Last weekend at his brother's baseball game, Joshua was in the 50's. Shannon gave home about 150 carbs and he still didn't go over 100. We struggled with it all night. With a little help from a friend, we decided to do a zero temp basal for 3 hours. We checked him at 3:00 am and he was a respectable 179 with arrows up on Dex. So we resumed his normal basal thinking all was good. At wake up, he was 62. This has been a struggle all week long. Shannon took him to his normal endo appointment and the doc said she thought he probably had some sort of intestinal virus. A week later, he is low again today. Are some batches of insulin stronger? Is he cured :) I just wish diabetes would pick a script and stick to it!