I have pku and i am pregnant but i came off my diet at 15-16 and im now 26 and 16+5 weeks pregnant and therefore have been back on the diet since may-june of this yr, I did have all the problems u listed that pku's that dont do diet have and i do still have some but i would never advise taking a low protein diet with out the formula (medication) ur body needs certain vitamins ect that is in the formula which we pku's dont get from foods on low protein diet cos we dont eat the foods with them in! So as i was told by my consultant for my pku i needed 2 eat plenty of normal foods even high protein foods 2 get these vitamins ect e.g milk, yoghurt, cheese, meat this is 2 ensure that ur body is not lacking in all the other things it needs from the formula. If ur mum was 2 do a low protein diet and take now formula she would very soon fall ill worse than if she didnt do the low protein diet as her body wont be getting the things it needs 2 function. I managed 16 yr's off my diet and apart from the slight problems i have which doesn't affect every1, i put mine down 2 an extremely hard childhood not 2 do with my pku and an even harder adulthood. I would just advise ur mum 2 eat things with all the good vitamins in n stuff like cheese, yoghurt ect but also eat plebty of lower protein foods as well just make sure she's gettin them vitamins n stuff. Well i hope i've helped in some way and plz add of msg me anytime, good luck with ur search about pku, but with out medication or health care professionals involved with ur mum and her pku there is not much u can really do! As the pku diet will only work well 4 ur mum with the medication with it, otherwise it'll just make ur mum ill.
Hope 2 hear from u soon and know how u and ur mum r doing!