Sick when drinking milk but fine when has it on cereal?!!?

My daughter is now nearly 15 months. Around 12 months I tried to switch her from formula to cows milk, she has had cows milk on her cereal since 9/10 months. At the time I wasn't sure but she seemed to be being sick 5/10 mins after having a couple of sips of milk, not a huge amount of sick but then she wasn't drinking a huge amount of milk!

So, she has been on formula ever since. I decided to try again now as it has been a few months and it's the same thing again. She is sick probably 5 mins or less after drinking the milk, again she only has a sip and only seems to bring up the couple of sips she has just had?

Seriously, am I going mad?? How can she possibly be ok having it on her cereal but not ok drinking it?? Has anyone else had this? I have tried watering the milk down but it had the same reaction?

She absolutely LOVES cheese and yoghurt and is never sick after eating them, she just isn't a sicky baby which is why it's so odd?

I haven't had a HV visit since she was 6/9 months or so (can't remember lol)and so I can't ask them, although I might try and ask at her weigh in, they're usually about as useful as a chocolate fireguard though.

Someone tell me they have the same!!!