Hi , I'm James DVM MRCVS and would like to help you with your question
sorry to hear about Marco .
I see his situation is more complex and is treated by his vet which is good .
In answer to you question / the cloudiness in the water can be due to Marco salivating more then normal . as you mentioned he has been sick recently which means he is would be producing more saliva and that will come out as he is drinking the water and mix with the it to make is more gray and cloudy.
In regards XXXXX XXXXX pink hue. there are several options :
1. Could be that Marco has a ulcers in his stomach (part of why he is vomiting as well) and this produces blood which is then brought up with his vomit .
2. it could be that due to his vomiting , the acid in his stomach causes wounds around his esophagus which bleed very gently and this is the blood which then comes up and gets in the drinking water giving it the pink color.
3. it might be an ongoing dental disease which was not very clear before but now with the cloudiness of the water it is much more visible (blood dripping of inflamed gums).
In short - I don't see it being caused by the anti Sickness tablets so you don't need to worry .
I hope this helps .
If you have any more questions please let me know and I shall do my best to help.
all the best to you both.
Please before you leave this chat do not forget to rate it