lump in throat?

my share horse had an odd and large soft lump on his neck just behind the jaw and much more pronounced on his off side today, kind of oblong and 5inches long , 3 or so across. The owner seemed to think it was ball of grass and tried to massage it down his troat. it did seem to go down a bit later after a wet feed but I'm worried it might be something more serious. he also had a sort of yellowy discharge from his nose breifly when he was eating..
Any ideas? Would be calling vet now if it was my horse but I'm still a novice so not entirely sure if it's something to worry about? I am very worried about him though. Help!!!
 
Im not an expert, but i would call the vet just to put your mind at rest, and if it is anything bad to catch it early. x
 
Sounds as if it could be a respiratory illness. Maybe nothing but would be as well to get it checked. Is he being kept seperate from other horses if he's snotty?
 
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