My dog is avoiding my room

Hello,

Untill 4 days ago my dog used to sleep with me for approx. 5 years in the same room, sometimes in his bed sometimes mine and sometimes on the floor, no matter how hot/cold it is he would remain here no matter what. 4 days ago in the middle of the night he woke up starting to scratch him self and bite the back paws a lot and very often and it would cause him to not sleep and that would continue on for 2 straight days (since it was easter couldnt take him to vet before) of almost no sleep ( during the day he was bit better so he would rest then) sometimes he would start to run also as if some sharp momentarily pain stroke him and he just got afraid and run'd away. I took him to vet and he said its most likely allergies so he gave him a shoot + anti bug thing on his neck and cleaned his glands. Itching, bitting lowered by 95% and random running from i'm assuming sharp pain dissapeared, he follows me to room many times , hops in his bed and then just stares at things like there is something in the room moving cause it feels like he is observing it for a while and then starts to make noises like he wants to go away from here. He tried to come to my room atleast 10 times and results are always the same. Ive cleaned whole room with high temperature steamer to kill every germ and sort of thing, cleaned his whole bed/ my bed, but result is the same, he comes but after few minutes he is just uncomfy being here, once we try to leave he does it with really high speed like something is about to chase him down. This doesnt happen anywhere else in the house besides my room.
I hope someone could help me out on what to do to make him come back to my room without being scared/uncomfy.

Breed of the dog is shih tzu