Is all her behaviour changed or just nappy changing times? Because if its just nappy changing then thats what babies do, they learn to roll around and struggle and make it as hard as possible and I'm sure a lot of parents on this board could tell you how at some point there nice still baby turn into a wiggling scream machine, all 4 of mine did. The screaming is probably simply that changing her nappy is not her idea of fun and she'd rather be doing something else. Its not a behaviour problem its normal development (IMO...I'm a parent not a doctor!).

Sounds normal development to me. But, I am not seeing what is going on. Was she immunized recently? Could be neurological reaction to shots. But if not, I would say, just normal turn in her development. Minimize restraining her. Try to change diaper when she is on her tumy. When needs cleaning, just put her in a bath.