Buy a small A6 notebook that will fit in your pocket and draw in colums yourself for all the information you want to record. Keep it with you so you can jot stuff down as it happens and then transfer the date into the "official" documents that you are required to keep such as the flock and medicine records.
The beauty of this is you can keep lots of extra records over and above the legal minimums if you want to, such as parentage of your lambs, birth weights, litter size etc. All useful stuff to know.