When do you start worrying about a brain tumour?

My son is 7M weighs 19 kg and is 113 cm tall he’s clumsy, lacks focus and memory, was failure to thrive until he started taking sandiogram (he’s at the max dose his dr said he could take), still having daily headaches, mood swings, nausea and vomiting sporadically every day. We’ve been fighting to get answers for 3 years now.... full blood count is fine thyroid, liver, and kidneys are fine

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