Hello! wondering if anyone can advise me, Oscar our bengal is howling NON STOP! its so bad im worried the neighbours will complain to the council about him

he had a bout of food poisoning last week after stealing some old tuna we found in the fridge whilst clearing it out, and had to go to the vets and was given an anti sickness injection but he's got the all clear but this week he has started incessantly crying and howling constantly nothing passifies him - we play with him, make sure he has food, fresh water, litter, he has two other cats for company, plenty of roaming space, i have even resorted to letting him wander in the garden when im watering the plants to quell his crying but as soon as we are in the house he is yelling at the top of his voice. the only thing that has changed is the next door neighbour had a baby on monday, and it cries a lot, we can hear it through the walls, it has that high pitched cry new borns have, could this be confusing him? he has never done this before, he's always been vocal, but not like this, to an extent where i dont know what to do. its not a distress yell like he does at the vets when he's in a box, just a sharp LOUD MAU MAU MAU yell. if its the new baby what on earth can i do or is that an inane thing to blame? our bath is currently full of ping pong balls through trying to find ways to calm him or entertain him and i cant keep giving him treats (they quieten him!) cause he'll get fat!!
TIA!