2 months ago my son accidentally forgot to flush so I was able to notice a bunch of stuff floating on top of the water. I thought he must have put detergent in the toilet bowl but he then told me that's how his pee is. I am now worried sick. :-( His urine is foamy almost all the time but sometimes there's this white residue/milky way-looking thing just floating on top right after he goes. It almost looks as if the water is about to develop mold on the surface but if you get really close to it, it's just bubbles. :-( It also separates in "blocks" if you put your finger in it (yes, gross, but there's nothing too gross for a mother), which is super weird.
Here are some pictures: https://drive.google.com/folderview?id=1UVSAvIabB3pPcKlxTBL5L9qu4lAfaBBY
Informed his pediatrician, did a urine culture and urinalysis and it all came back negative. No traces of protein, nothing at all, really! :-( I have been monitoring his water intake for years and he drinks 1.5 l of just water every day so he can't be dehydrated either. The foam doesn't go away on its own unless you flush. Stopped dairy for 10 days, changed the water, stopped giving him any protein for over a week, etc, to no avail. He has no other symptoms, urine doesn't have any atypical smell, he sleeps really well, is a great eater (eats a ton of veggies and fruit every day) and a very happy child overall. I keep him away from junk food/unhealthy fats and sugar, etc. He only drinks water but twice a week he gets a glass of milk. No juice! Just trying to give you a better picture. I have noticed this change in his urine 2 months ago. At that time I have also stopped the vitamins I normally give him (multivitamin, vit.D, vit. C, probiotics, and elderberry syrup). Resuming that today - trying to see if there's a vitamin deficiency that shows up once I stopped the vitamins?
Does anybody have any ideas what this could be?
Thank you so very much!