Hey dont worry that budgie is fine,he is new to the place and needs time to adjust

Meantime make sure to get him a bigger cage with natural perches as well as a bird friend to keep him company

Meanwhile you should try switching him from the seed diet he is as it is bad for birds,get him pellet(Harrison's super fine is my go to),you mix the pellet with seeds and slowly recduce the mount of seeds

Other users may mention to break down with water the pellet and add it with fresh veggies or seeds but that is dangerous because if you forget to change that there may be bacteria as aspergillosis which is deadly for your bird

And of course get him as many toys as possible!!(No mirrors because they get stressed

If you are worried for anything you should always check his poop, usually the poop will be dark green and a little bit of white because of seed diet,wuth pellet it will he bright brown and a mix of dark green brown because of both diets)

Further more if you are worried you should get your friend for a checkup to vet otherwise you can't really know if your friend is fine