Constant sore throat

Hello, my son is now 3 years old. He has a few minor medical problems in his life.
He had reflux when he was born. His poo is never really normal often quite loose and sometimes has random sickness. He has had 3 seizures first at 15 months next at 17 months then one at 26 months, all undiagnosed.
His sleep is always broken he wakes atleast once a night very angry shouting so we have to calm him, he also talks in his sleep.
For the last few months he has complained of a sore throat in the night and often has a croaky voice for a short while the next day, we just put this down to him shouting alot and also he talks alot! However i also have noticed that he watches my mouth carefully when i talk and doesnt always understand what people say, he often ignored people and i dont no if he doesnt hear or doesnt listen. He is ok development wise, he gets frustrated easily when talking and his speaking isnt that great he mis prounounces many words which i no is common at this age anyway, but when i put all these things together it makes me wonder could it be something else wrong with him.
He had a hearing test when was 8 months old which he passed. He is quite hyperactive anyway but often strikes out in anger for no apparent reason and he gets upset and angry with no apparent reason.

I really hope someone may be able to offer me some advice if this could be anything else

Thanks