Haven't been doing it for years but my system seems to work:
Excel with 6 rows for each animal, merged on the left to write some info about the individual animal. Lock that big merged cell so it stays put when you scroll.

2 rows each for feeding - one for the date and one for 'comments' like the prey size and type.

2 rows each for shedding - one for dates and one for comments like how many pieces, whether eyes were clear, etc.

2 rows each for 'other' which would be weights, full cleanings, weird behavior changes, etc. with 1 row for the date and one for comments.

You can use any free cloud storage app and access it from your computer OR your tablet / laptop.

Unless of course by 'tablet or notebook' you did not mean computers and literally meant pen and paper, in which case please disregard this post